Methods and systems for processing cellulosic biomass

ABSTRACT

Digestion of cellulosic biomass solids may be complicated by release of lignin therefrom. Methods and systems for processing a reaction product containing lignin-derived products, such as phenolics, can comprise hydrotreating the reaction product to convert the lignin-derived products to desired higher molecular weight compounds. The methods can further include separating the higher molecular weight compounds from unconverted products, such as unconverted phenolics, and recycling the unconverted phenolics for use as at least a portion of the digestion solvent and for further conversion to desired higher molecular weight compounds with additional hydrotreatment. The methods and systems can further include generating hydrogen with the further hydrotreatment.

This present application claims the benefit of U.S. Patent ApplicationNo. 62/058,618 filed Oct. 1, 2014, the disclosure of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

This section is intended to introduce various aspects of the art, whichmay be associated with exemplary embodiments of the present invention.This discussion is believed to assist in providing a framework tofacilitate a better understanding of particular aspects of the presentinvention. Accordingly, it should be understood that this section shouldbe read in this light, and not necessarily as admissions of any priorart.

The present disclosure generally relates to digestion of cellulosicbiomass solids, and, more specifically, to methods for processing areaction product comprising lignin that may be obtained by digestion ofcellulosic biomass.

A number of substances of commercial significance may be produced fromnatural sources, including biomass. Cellulosic biomass may beparticularly advantageous in this regard due to the versatility of theabundant carbohydrates found therein in various forms. As used herein,the term “cellulosic biomass” refers to a living or formerly livingbiological material that contains cellulose. The lignocellulosicmaterial found in the cell walls of higher plants is the world's largestsource of carbohydrates. Materials commonly produced from cellulosicbiomass may include, for example, paper and pulpwood via partialdigestion, biofuels, including bioethanol by fermentation.

Development of fossil fuel alternatives derived from renewable resourceshave received recent attention. Cellulosic biomass has garneredparticular attention in this regard due to its abundance and theversatility of the various constituents found therein, particularlycellulose and other carbohydrates. Despite promise and intense interest,the development and implementation of bio-based fuel technology has beenslow. Existing technologies have heretofore produced fuels having a lowenergy density (e.g., bioethanol) and/or that are not fully compatiblewith existing engine designs and transportation infrastructure (e.g.,methanol, biodiesel, Fischer-Tropsch diesel, hydrogen, and methane).Moreover, conventional bio-based processes have typically producedintermediates in dilute aqueous solutions (>50% water by weight) thatare difficult to further process. Energy- and cost-efficient processesfor processing cellulosic biomass into fuel blends having similarcompositions to fossil fuels would be highly desirable to address theforegoing issues and others.

Further, in addition to the desired carbohydrates, other substances maybe present within cellulosic biomass that can be especially problematicto deal with in an energy- and cost-efficient manner. For example,during cellulosic biomass processing, the significant quantities oflignin present in cellulosic biomass may lead to fouling of processingequipment, potentially leading to costly system down time. Thesignificant lignin quantities can also lead to realization of arelatively low conversion of the cellulosic biomass into useablesubstances per unit weight of feedstock.

As evidenced by the foregoing, the efficient conversion of cellulosicbiomass into fuel blends and other materials is a complex problem thatpresents immense engineering challenges. The present disclosureaddresses these challenges and provides related advantages as well.

SUMMARY

The present disclosure generally relates to digestion of cellulosicbiomass solids, and, more specifically, to methods for processinglignin-derived phenolics that may be obtained in conjunction withhydrothermal digestion of cellulosic biomass solids. According tocertain aspects, there is provided a method comprising: providing afirst reaction content to a reactor in a first reaction zone, where thefirst reaction content comprises cellulosic biomass solids, molecularhydrogen, a catalyst capable of activating molecular hydrogen, and adigestion solvent; heating the first reaction content to form a firstreaction product comprising phenolics and an alcoholic component;providing a second reaction content to a reactor in a second reactionzone, where the second reaction content comprises the first reactionproduct, molecular hydrogen, and a catalyst capable of activatingmolecular hydrogen; heating the second reaction content to form a secondreaction product comprising hydrocarbons converted from phenolics andunconverted phenolics, providing the reactor in the second reaction zonewith conditions configured to generate molecular hydrogen, wherein atleast one of said conditions comprises providing the reactor in thesecond reaction zone with a pressure of less than 200 bar; separating anunconverted phenolics fraction from the second reaction product;providing a first portion of the unconverted phenolics fraction to thereactor in the first reaction zone; and providing a second portion ofthe unconverted phenolics fraction to the reactor in the second reactionzone.

The hydrocarbon compounds include at least one of an alkane, an alkene,a cycloalkane, a cycloalkene, and an alkyl derivative or substituent ofthe cycloalkane and/or cycloalkene, such as any one of cyclohexane,cyclohexene, propyl cyclopentane, propyl cyclopentene, propylcyclohexane, propyl cyclohexene, anisole, propyl benzene, cyclohexanone,methyl cyclohexanone, methyl propyl benzene, and any combinationthereof.

In some embodiments, the second reaction content has a concentration ofphenolics of 50% or less by weight based on the total weight of thesecond reaction content. In some embodiments, the second reactioncontent has a water concentration of at least 10% by weight based on thetotal weight of the second reaction content. In some embodiments, theunconverted phenolics fraction comprises greater than 50% of the amountof phenolics in the second reaction product from which the unconvertedphenolics fraction is separated. In some embodiments, at least a portionof triols and glycol in the alcoholic component is converted tomonohydric alcohols.

The first reaction content can be heated to a temperature in a range ofabout 190 to 260 degrees C. The second reaction content can be heated toa temperature in a range of about 210 to 300 degrees C. The reactor inthe first reaction zone can have a total pressure of at least 30 bar.The reactor in the second reaction zone can have a total pressure of atleast 30 bar. The reactor in the second reaction zone can have a totalpressure that is lower than a total pressure of the reactor in the firstreaction zone.

In some embodiments, the catalyst in the first reaction contentcomprises fluidly mobile catalyst particulates. In some embodiments, thecatalyst in the reactor in the second reaction content comprises fluidlymobile catalyst particulates. The fluidly mobile catalyst particulatesin the second reaction content can comprise fluidly mobile catalystparticulates from the first reaction content. In some embodiments, atleast one of the first reaction zone and the second reaction zonecomprises a slurry reactor. In some embodiments, at least one of thefirst reaction zone and the second reaction zone comprises an ebullatingbed reactor. The first reaction zone can comprise an ebullating bedreactor while the second reaction zone can comprise at least one of afixed bed reactor and a trickle bed reactor. The method of claim 1,wherein the first reaction zone comprises a slurry reactor and thesecond reaction zone comprises at least one of a fixed bed reactor and atrickle bed reactor.

In some embodiments, the method further comprises providing to thereactor in the second reaction zone a catalyst different from thecatalyst in the reactor in the first reaction zone. In some embodiments,the method further comprises increasing the catalytic activity in thereactor in the second reaction zone to increase hydrogen generation.

The features and advantages of embodiments provided by the presentdisclosure will be readily apparent to one having ordinary skill in theart upon a reading of the description of the embodiments that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures are included to illustrate certain aspects of thepresent disclosure, and should not be viewed as an exclusive embodiment.The subject matter disclosed is capable of considerable modifications,alterations, combinations, and equivalents in form and function, as willoccur to one having ordinary skill in the art and the benefit of thisdisclosure.

FIG. 1 shows a schematic of a first illustrative embodiment forprocessing cellulosic biomass according some aspects provided by thisdisclosure.

FIG. 2 shows a schematic of a second illustrative embodiment forprocessing cellulosic biomass according some aspects provided by thisdisclosure.

FIG. 3 shows a schematic of a third illustrative embodiment forprocessing cellulosic biomass according some aspects provided by thisdisclosure.

DETAILED DESCRIPTION

The present disclosure generally provides methods for processingcellulosic biomass into a fuel product, particularly throughhydrothermal reactions. Cellulosic biomass is particularly advantageousbecause of the versatility of the abundant carbohydrates found thereinin various forms. As used herein, the term “cellulosic biomass” refersto a living or formerly living biological material that containscellulose. The lignocellulosic material found in the cell walls ofhigher plants is one of the world's largest source of carbohydrates.

Plants have primary cell walls and secondary cell walls. The primarycell wall contains three major polysaccharides (cellulose, pectin, andhemicellulose) and one group of glycoproteins. The secondary cell wallalso contains polysaccharides polymeric lignin that is covalentlycrosslinked to hemicellulose. The complex mixture of constituents thatis co-present with the cellulose can make its processing difficult, asdiscussed hereinafter. Lignin, in particular, may be an especiallydifficult constituent to deal with.

When converting cellulosic biomass into fuel blends and other materials,cellulose and other complex carbohydrates therein can be extracted andtransformed into simpler organic molecules, which can be furtherprocessed thereafter. Digestion is one way in which cellulose and othercomplex carbohydrates may be converted into a more usable form.Digestion processes can break down cellulose and other complexcarbohydrates within cellulosic biomass into simpler, solublecarbohydrates that are suitable for further transformation throughdownstream further processing reactions. As used herein, the term“soluble carbohydrates” refers to monosaccharides or polysaccharidesthat become solubilized in a digestion process.

The issues associated with converting cellulosic biomass into fuelblends in an energy- and cost-efficient manner using digestion are notonly complex, but they are entirely different than those that areencountered in the digestion processes commonly used in the paper andpulpwood industry. Since the intent of cellulosic biomass digestion inthe paper and pulpwood industry is to retain a solid material (e.g.,wood pulp), incomplete digestion is usually performed at lowtemperatures (e.g., less than about 200° C.) for a fairly short periodof time (e.g., between two to four hours). In contrast, digestionprocesses suitable for converting cellulosic biomass into fuel blendsand other materials are ideally configured to maximize yields bysolubilizing as much of the original cellulosic biomass charge aspossible in a high-throughput manner. Paper and pulpwood digestionprocesses also typically remove lignin from the raw cellulosic biomassprior to pulp formation. Although digestion processes used in connectionwith forming fuel blends and other materials may likewise remove ligninprior to digestion, these extra process steps may impact the energyefficiency and cost of the biomass conversion process. The presence oflignin during high-conversion cellulosic biomass digestion may beparticularly problematic.

Production of soluble carbohydrates for use in fuel blends and othermaterials via routine modification of paper and pulpwood digestionprocesses is not believed to be economically feasible for a number ofreasons. Simply running the digestion processes of the paper andpulpwood industry for a longer period of time to produce more solublecarbohydrates is undesirable from a throughput standpoint. Use ofdigestion promoters such as strong alkalis, strong acids, or sulfites toaccelerate the digestion rate can increase process costs and complexitydue to post-processing separation steps and the possible need to protectdownstream components from these agents. Accelerating the digestion rateby increasing the digestion temperature can actually reduce yields dueto thermal degradation of soluble carbohydrates that can occur atelevated digestion temperatures, particularly over extended periods oftime. Once produced by digestion, soluble carbohydrates are veryreactive and can rapidly degrade to produce caramelans and other heavyends degradation products, especially under higher temperatureconditions, such as above about 150 degrees C. Use of higher digestiontemperatures can also be undesirable from an energy efficiencystandpoint. Any of these difficulties can defeat the economic viabilityof fuel blends derived from cellulosic biomass.

A particularly effective manner in which soluble carbohydrates may beformed is through hydrothermal digestion, and in which the solublecarbohydrates may be converted into more stable compounds is throughsubjecting them to one or more catalytic reduction, which may includehydrogenation and/or hydrogenolysis reactions. Stabilizing solublecarbohydrates through conducting one or more catalytic reductionreactions may allow digestion of cellulosic biomass to take place athigher temperatures than would otherwise be possible without undulysacrificing yields. Depending on the reaction conditions and catalystused, reaction products formed as a result of conducting one or morecatalytic reduction reactions on soluble carbohydrates may comprise oneor more alcohol functional groups, particularly including triols,glycol, monohydric alcohols, and any combination thereof, some of whichmay also include a residual carbonyl functionality (e.g., an aldehyde ora ketone). The compounds in the alcoholic component can be described asoxygenates where the compounds comprise one or more oxygen-containingfunctional group, such as a hydroxyl group or a carbonyl group.Non-limiting examples of oxygenates include an aldehyde, a ketone, analcohol, furan, an ether, or any combination thereof. Such reactionproducts are more thermally stable than soluble carbohydrates and may bereadily transformable into fuel blends and other materials throughconducting one or more downstream further processing reactions. Inaddition, the foregoing types of reaction products are good solvents inwhich a hydrothermal digestion may be performed, thereby promotingsolubilization of soluble carbohydrates as their reaction products.

Hydrothermal digestion of a cellulosic biomass can include heating ofthe cellulosic biomass and a digestion solvent in the presence ofmolecular hydrogen and a catalyst capable of activating the molecularhydrogen (which can also be referred to herein as a “hydrogen-activatingcatalyst” or “hydrocatalytic catalyst”). In such approaches, thehydrothermal digestion of cellulosic biomass and the catalytic reductionof soluble carbohydrates produced therefrom may take place in the samevessel, which can be referred to as “in situ catalytic reductionreaction processes.” As such, digestion processes suitable forconverting cellulosic biomass into fuel blends and other materials arepreferably configured to maximize yields by solubilizing as much of theoriginal cellulosic biomass charge as possible in a high-throughputmanner. In situ catalytic reduction reaction processes may also beparticularly advantageous from an energy efficiency standpoint, sincehydrothermal digestion of cellulosic biomass is an endothermic process,whereas catalytic reduction reactions are exothermic. Thus, the excessheat generated by the in situ catalytic reduction reaction(s) may beutilized to drive the hydrothermal digestion with little opportunity forheat transfer loss to occur, thereby lowering the amount of additionalheat energy input needed to conduct the digestion.

While soluble carbohydrates and alcoholic compounds formed therefrom aredesirable products, processing of cellulosic biomass also needs toaddress the presence of lignin during high-conversion cellulosic biomassdigestion, which may be particularly problematic. Although a digestionsolvent may also promote solubilization of lignin, the lignin may stillbe difficult to effectively process due to its poor solubility andprecipitation propensity. In particular, during cellulosic biomassprocessing, the significant quantities of lignin present in cellulosicbiomass may lead to fouling of processing equipment, potentially leadingto costly system down time. The significant lignin quantities can alsolead to realization of a relatively low conversion of the cellulosicbiomass into useable substances per unit weight of cellulosic biomassfeedstock.

In light of the advantages of hydrothermal digestion and catalyticreduction and problems presented by lignin the present disclosureprovides methods and systems for processing cellulosic biomass byconverting phenolics generated from hydrothermal processing ofcellulosic biomass to more desirable products, particularly hydrocarboncompounds. The terms “hydrocarbon compounds,” “hydrocarbons,” or relatedterms refer to compounds comprising hydrogen and carbon atoms that donot have a phenolic functional group, which is a hydroxyl group (—OH)bonded to an aromatic hydrocarbon group. Illustrative, non-limitinghydrocarbon compounds include alkanes, alkenes, cycloalkanes and theiralkyl substituents or derivatives, and cycloalkenes and their alkylsubstituents or derivatives, which can be suitable for use in fuelcomposition, for instance gasoline or diesel. For instance, illustrativehydrocarbon compounds can include but are not limited to cyclohexane,cyclohexene, propyl cyclopentane, propyl cyclopentene, propylcyclohexane, propyl cyclohexene, anisole, propyl benzene, cyclohexanone,methyl cyclohexanone, and methyl propyl benzene.

Cellulosic biomass processing can provide for lignin reversion, e.g.,reversion of lignin to phenols and conversion of phenolics derived fromlignin to hydrocarbons. As mentioned, processing of cellulosic biomasscan include hydrothermally digesting cellulosic biomass and carrying outa catalytic reduction reaction of soluble carbohydrates. This can beachieved via in situ catalytic reduction reaction, which involvesheating the cellulosic biomass and a digestion solvent in the presenceof molecular hydrogen and a catalyst capable of activating molecularhydrogen. The hydrothermal digestion and catalytic reduction cangenerate a first reaction product comprising phenolics derived fromlignin in the cellulosic biomass and an alcoholic component formed froma catalytic reduction reaction of soluble carbohydrates derived from thecellulosic biomass. The term “alcoholic component” refers to anoxygenate where the oxygenate can be a monohydric alcohol, a glycol, atriol, or any combination thereof. As used herein, the term “glycol”will refer to compounds containing two alcohol functional groups, twoalcohol functional groups and a carbonyl functionality, or anycombination thereof. As used herein, the term “carbonyl functionality”will refer to an aldehyde functionality or a ketone functionality. Insome embodiments, a glycol may comprise a significant fraction of thereaction product. Although a glycol may comprise a significant fractionof the reaction product, it is to be recognized that other alcohols,including triols and monohydric alcohols, for example, may also bepresent. Further, any of these alcohols may further include a carbonylfunctionality. As used herein, the term “triol” will refer to compoundscontaining three alcohol functional groups, three alcohol functionalgroups and a carbonyl functionality, and any combination thereof. Asused herein, the term “monohydric alcohol” will refer to compoundscontaining one alcohol functional group, one alcohol functional groupand a carbonyl functionality, and any combination thereof. The term“phenolics” or “phenols” has its ordinary meaning, which generallyrefers to a class of compounds that contain a hydroxyl group (—OH)bonded to an aromatic hydrocarbon group.

The in situ catalytic reduction reaction can be considered a firsthydrothermal reaction. At least a portion of the phenolics in the firstreaction product can be converted to hydrocarbon compounds by a secondhydrothermal reaction where the first reaction product is heated in thepresence of molecular hydrogen and catalyst capable activating molecularhydrogen. Optionally, at least some of the alcoholic component in thefirst reaction product, such as glycol or triol, can also be convertedto monohydric alcohol in the second hydrothermal reaction.

Unconverted phenolics—phenolics that have not been converted tohydrocarbons (meaning compounds that still contain a hydroxyl groupbonded to an aromatic hydrocarbon group)—may be recycled or returned tothe first hydrothermal reaction and the second hydrothermal reaction sothey can continue to be converted to hydrocarbons. For instance,phenolics that have not been converted may be used as at least a portionof the digestion solvent in the first hydrothermal reaction. Phenolicsthat have not been converted may also be recycled to the secondhydrothermal reaction where they are heated with the first reactionproduct to generate additional hydrocarbons. As such, it may be saidthat—in principle—lignin in the form of phenolics can potentially berecycled until they are substantially eliminated through one or morehydrothermal digestion, catalytic reduction, and reversion reactions.

The first reaction product may contain catalyst from the hydrothermaldigestion reaction accumulated therein. As such, the catalyst in thefirst hydrothermal reaction generating the first reaction product may bethe same as the catalyst in the second hydrothermal reaction generatingcertain hydrocarbons from phenolics, and optionally monohydric alcoholfrom glycol or triol. If catalyst accumulated in the first reactionproduct is removed, the second hydrothermal reaction may use a differentcatalyst than the first hydrothermal reaction. The temperature to whichthe cellulosic biomass, digestion solvent, molecular hydrogen, andcatalyst are heated in the first hydrothermal reaction may be lower thanthe temperature to which the first reaction product, molecular hydrogen,and catalyst are heated in the second hydrothermal reaction. Hydrogenmay be generated in the second hydrothermal reaction, which may be usedin the hydrothermal reactions themselves. Various conditions of thehydrothermal reactions may be optimized for hydrogen reaction.

It had been found that a second hydrothermal reaction having a lowphenolics concentration can provide better yields of hydrocarbons thanone with a high concentration of phenolics. That is, lignin reversioncan be better when the concentration of phenolics in the reactioncontent of the second hydrothermal reaction is low versus when thephenolics concentration is high. For instance, low phenolicsconcentration in the second hydrothermal reaction is a concentration ofup to 50% by weight based on the total weight of the content of thesecond hydrothermal reaction. Non-limiting illustrative phenolicsconcentrations of the reaction content in the second hydrothermalreaction can be in a range of about 0.1% to 50% by weight, and anyamount in between, including less than 45%, less than 40%, less than35%, less than 30%, less than 25%, less than 20%, less than 15%, lessthan 10%, or less than 5% by weight, based on the total content weightof the second hydrothermal reaction.

Lignin reversion, including conversion of lignin to phenols and/orconversion of phenolics to hydrocarbon compounds, can be improved if theconversion is accomplished in the presence of water. That is thephenolics concentration in the second hydrothermal reaction of 50% orless by weight of the content of the second hydrothermal reaction can beachieved at least in part with water. For instance, the concentration ofwater in the second hydrothermal reaction can be at least 10% by weightbased on the total weight of the content of the second hydrothermalreaction. Non-limiting illustrative water concentration of the reactioncontent in the second hydrothermal reaction can be at least 10%, atleast 15%, at least 20%, at least 25%, at least 30%, at least 35%, or atleast 40% by weight, based on the total content weight of the secondhydrothermal reaction.

Optionally, as mentioned above, the second hydrothermal reaction canalso provide for conversion of at least some of the alcoholic component,such as glycol or triols, in the first reaction product to monohydricalcohol. As can be seen, the processes and systems described herein canreduce phenolics contamination of desirable products by providing forconversion of phenolics, including unconverted phenolics, into desirableproducts such as hydrocarbons. In particular, the second hydrothermalreaction and can hydrotreat compounds that are hydrotreatable to produceproducts, such as certain hydrocarbons and optionally monohydricalcohol, that have boiling points further away from phenolics. Thegreater difference in boiling points can facilitate separation ofphenolics still present in the reaction product from desired compoundsthat are intended for further processing into fuel products.

Accordingly, the present disclosure provides a method comprisingproviding a first reaction content to a reactor in a first reactionzone, where the first reaction content comprises cellulosic biomasssolids, molecular hydrogen, a catalyst capable of activating molecularhydrogen, and a digestion solvent; heating the first reaction content toform a first reaction product comprising phenolics and an alcoholiccomponent; providing a second reaction content to a reactor in a secondreaction zone, where the second reaction content comprises the firstreaction product, molecular hydrogen, and a catalyst capable ofactivating molecular hydrogen; heating the second reaction content toform a second reaction product comprising unconverted phenolics andhydrocarbons converted from phenolics, where the reactor in the secondreaction zone has a pressure of less than 200 bar; separating anunconverted phenolics fraction from the second reaction product;providing a first portion of the unconverted phenolics fraction to thereactor in the first reaction zone; and providing a second portion ofthe unconverted phenolics fraction to the reactor in the second reactionzone.

Unless otherwise specified, it is to be understood that use of the terms“biomass” or “cellulosic biomass” may be synonymous. The cellulosicbiomass may be in any size, shape, or form. The cellulosic biomass maybe natively present in any of these solid sizes, shapes, or forms, orthey may be further processed prior to digestion. The cellulosic biomassmay be chopped, ground, shredded, pulverized, and the like to produce adesired size prior to hydrothermal digestion. The cellulosic biomass maybe washed (e.g., with water, an acid, a base, combinations thereof, andthe like) prior to digestion taking place.

Any type of suitable cellulosic biomass source may be used. Suitablecellulosic biomass sources may include, for example, forestry residues,agricultural residues, herbaceous material, municipal solid wastes,waste and recycled paper, pulp and paper mill residues, and anycombination thereof. Thus, in some embodiments, a suitable cellulosicbiomass may include, for example, corn stover, straw, bagasse,miscanthus, sorghum residue, switch grass, bamboo, water hyacinth,hardwood, hardwood chips, hardwood pulp, softwood, softwood chips,softwood pulp, duckweed and any combination thereof. Leaves, roots,seeds, stalks, husks, and the like may be used as a source of thecellulosic biomass. Common sources of cellulosic biomass may include,for example, agricultural wastes (e.g., corn stalks, straw, seed hulls,sugarcane leavings, nut shells, and the like), wood materials (e.g.,wood or bark, sawdust, timber slash, mill scrap, and the like),municipal waste (e.g., waste paper, yard clippings or debris, and thelike), and energy crops (e.g., poplars, willows, switch grass, alfalfa,prairie bluestream, corn, soybeans, and the like). The cellulosicbiomass may be chosen based upon considerations such as, for example,cellulose and/or hemicellulose content, lignin content, growingtime/season, growing location/transportation cost, growing costs,harvesting costs, and the like.

Illustrative carbohydrates that may be present in cellulosic biomasssolids include, for example, sugars, sugar alcohols, celluloses,lignocelluloses, hemicelluloses, and any combination thereof. Asmentioned, once soluble carbohydrates have been produced throughhydrothermal digestion according to the embodiments described herein,the soluble carbohydrates may be transformed into a more stable reactionproduct comprising an alcoholic component, which may comprise amonohydric alcohol, a glycol, a triol, or any combination thereof invarious embodiments.

Any type of suitable catalyst capable of activating hydrogen can be usedin any reactor suitable for use with the selected catalyst(s) for thefirst and second hydrothermal reactions. For example, at least one ofthe first and second hydrothermal reactions can be carried out usingfluidly mobile catalyst particles that can be at least partiallysuspended in a fluid phase via gas flow, liquid flow, mechanicalagitation, or any combination thereof in a reactor. Various conditionscan be implemented so that the fluidly mobile catalyst particles do notget carried out of the reactor by the fluid flowing through the reactor.A reactor operating under these circumstances can be called anebullating bed reactor in part because the catalyst particles remain inthe reactor to form a catalytic bed. It is understood that one ofordinary skill in the art can select the various conditions to achievean ebullating bed reactor. For instance, a suitable concentration ofcatalyst and/or catalyst size can be selected to obtain the desiredreactor conditions.

On the other hand, the conditions can be modified so that the fluidlymobile catalyst particles flow with the biomass solids through thereactor. A reactor operating under these circumstances can be called aslurry reactor. Adequate catalyst distribution is desirable in a slurryreactor so that soluble carbohydrates formed during hydrothermaldigestion may be intercepted and converted into more stable compoundsbefore they have had an opportunity to significantly degrade, even underthermal conditions that otherwise promote their degradation.

The second hydrothermal reaction can also be carried out using acatalyst that does not comprise fluidly mobile catalyst particles. Forexample, the second hydrothermal reaction can be carried out in a fixedbed reactor or a trickle bed reactor, which are known by one of ordinaryskill in the art. For instance, during operation of a fixed bed ortrickle bed reactor and fluid is flowing through the reactor, the heightof the bed does not increase to greater than 10% as compared to whenfluid is not flowing through the reactor.

If a reactor with a catalyst that does not comprise fluidly mobilecatalyst particles is used in the second hydrothermal reaction, apossible issue may be clogging of the bed by cellulosic particulates inthe first reaction product from the digestion. As cellulosic biomassbreaks apart during digestion, smaller and smaller particulates may beproduced until only insoluble materials remain. Cellulosic particulatesmay also be present in native cellulosic biomass before digestion takesplace. One way of handling cellulosic particulates can be use of ascreen at a fluid outlet of the hydrothermal digestion unit to assist inmaintaining the cellulosic fines therein. At a certain size, thecellulosic particulates may pass through the screen of the hydrothermaldigestion unit and enter at least the reactor in the second reactionzone.

Another way to address cellulosic particulates, particularly ones thatare sufficiently small to pass through screens, is the methods andsystems disclosed in commonly owned U.S. Application Publication No.2013/0152456 (“the '456 publication”), the disclosure of which isincorporated herein in its entirety. In general, the '456 publicationdiscloses a solids separation unit to which the first reaction productcan be routed to have at least a portion of the cellulosic particulatesremoved before it enters a reactor in the second reaction zone. Thesolids separation unit can comprise one or more filters, where at leastone of the filters can be backflushed to remove cellulosic finestherefrom, while one or more of the other filters remain in fluidcommunication with an inlet of the reactor in the second reaction zone.

If more than one filter is used, the filters may be connected inparallel to one another or they may be arranged on a rotatable filterarray. At least one of the filters may be backflushed while fluid flowcontinues through at least one of the remaining filters in a forwardflow direction. In such arrangements of the plurality of filters, thefirst reaction product can be continually provided to a reactor in thesecond reaction zone. Alternatively, each of the plurality of filtersmay be backflushed at the same time, such that the flow of the firstreaction product to the reactor in the second reaction zone isinterrupted or a single filter may be used, with more frequentbackflushing taking place. The one or more filters used may be of anytype capable of affecting separation of solids from a fluid phase.Suitable filters may include, for example, surface filters and depthfilters. Surface filters may include, for example, filter papers,membranes, porous solid media, and the like. Depth filters may include,for example, a column or plug of porous media designed to trap solidswithin its core structure.

Yet another way of addressing the cellulosic fines is disclosed incommonly owned U.S. Application Publication No. 2013/0158308 (“the '308publication”), the disclosure of which is incorporated herein in itsentirety. In general, like the '456 publication mentioned above, the'308 publication also discloses a solids separation unit to which thefirst reaction product can be routed to have at least a portion of thecellulosic particulates removed before it enters a reactor in the secondreaction zone. In addition to or instead of the one or more filters, thesolids separation unit of the '308 publication can also comprise acentripetal force-based separation mechanism. Such centripetalforce-based separation mechanism can also be commonly referred to in theart as centrifugal force-based separation mechanisms and/or vortex-basedseparation mechanisms. For instance, a suitable centripetal force-basedseparation mechanism may comprise a hydroclone (also known in the art asa hydrocyclone). It is understood that the processes and systemsdescribed herein can employ other suitable ways of separating orremoving the cellulosic biomass particles in the first reaction productknown to one of ordinary skill in the art, other than those that hadbeen mentioned herein.

In some embodiments, catalysts capable of activating molecular hydrogenmay comprise a metal such as, for example, Cr, Mo, W, Re, Mn, Cu, Cd,Fe, Co, Ni, Pt, Pd, Rh, Ru, Ir, Os, and alloys or any combinationthereof, either alone or with promoters such as Au, Ag, Cr, Zn, Mn, Sn,Bi, B, O, and alloys or any combination thereof. In some embodiments,the catalysts and promoters may allow for various hydrothermalreactions, such as hydrogenation and hydrogenolysis reactions, to occurat the same time or in succession of one another. In some embodiments,such catalysts may also comprise a carbonaceous pyropolymer catalystcontaining transition metals (e.g., Cr, Mo, W, Re, Mn, Cu, and Cd) orGroup VIII metals (e.g., Fe, Co, Ni, Pt, Pd, Rh, Ru, Ir, and Os). Insome embodiments, the foregoing catalysts may be combined with analkaline earth metal oxide or adhered to a catalytically active support.In some or other embodiments, the catalyst capable of activatingmolecular hydrogen may be deposited on a catalyst support that is notitself catalytically active.

In some embodiments, the catalyst used in the first and/or secondhydrothermal reaction may comprise a poison-tolerant catalyst. As usedherein the term “poison-tolerant catalyst” refers to a catalyst that iscapable of activating molecular hydrogen without needing to beregenerated or replaced due to low catalytic activity for at least about12 hours of continuous operation. Use of a poison-tolerant catalyst maybe particularly desirable when reacting soluble carbohydrates derivedfrom cellulosic biomass solids that have not had catalyst poisonsremoved therefrom. Catalysts that are not poison tolerant may also beused to achieve a similar result, but they may need to be regenerated orreplaced more frequently than does a poison-tolerant catalyst.

Suitable poison-tolerant catalysts may include, for example, sulfidedcatalysts. In some or other embodiments, nitrided catalysts may be usedas poison-tolerant catalysts. Sulfided catalysts suitable for activatingmolecular hydrogen are described in commonly owned U.S. patentapplication Ser. No. 13/495,785, and 61/553,591, each of which isincorporated herein by reference in its entirety. In more particularembodiments, the poison-tolerant catalyst may comprise a sulfidedcobalt-molybdate catalyst, such as a catalyst comprising about 1-10 wt.% cobalt oxide and up to about 30 wt. % molybdenum trioxide. In otherembodiments, catalysts containing Pt or Pd may also be effectivepoison-tolerant catalysts for use in the techniques described herein.When mediating in situ catalytic reduction reaction processes, sulfidedcatalysts may be particularly well suited to form reaction productscomprising a substantial fraction of glycols (e.g., C₂-C₆ glycols)without producing excessive amounts of the corresponding monohydricalcohols. Although poison-tolerant catalysts, particularly sulfidedcatalysts, may be well suited for forming glycols from solublecarbohydrates, it is to be recognized that other types of catalysts,which may not necessarily be poison-tolerant, may also be used toachieve a like result in alternative embodiments. As will be recognizedby one having ordinary skill in the art, various reaction parameters(e.g., temperature, pressure, catalyst composition, introduction ofother components, and the like) may be modified to favor the formationof a desired reaction product. Given the benefit of the presentdisclosure, one having ordinary skill in the art will be able to altervarious reaction parameters to change the product distribution obtainedfrom a particular catalyst and set of reactants.

If fluidly mobile catalyst particles are used, sulfiding may be achievedby dispersing the catalyst particles in a fluid phase and adding asulfiding agent thereto. Suitable sulfiding agents may include, forexample, organic sulfoxides (e.g., dimethyl sulfoxide), hydrogensulfide, salts of hydrogen sulfide (e.g., NaSH), and the like. In someembodiments, the catalyst particles may be concentrated in the fluidphase after sulfiding, and the concentrated slurry may then beintroduced to the cellulosic biomass solids using fluid flow.Illustrative techniques for catalyst sulfiding that may be used inconjunction with the methods described herein are described in UnitedStates Patent Application Publication No. 20100236988 and incorporatedherein by reference in its entirety.

The catalyst particles may have a particulate size of about 250 micronsor less, about 100 microns or less, or about 10 microns or less. Theminimum particulate size of the catalyst particles may be about 1micron. The catalyst particles may comprise catalyst fines. As usedherein, the term “catalyst fines” refers to solid catalysts having anominal particulate size of about 100 microns or less. Catalyst finesmay be generated from catalyst production processes, for example, duringextrusion of solid catalysts. Catalyst fines may also be produced bygrinding larger catalyst solids or during regeneration of catalystsolids. Suitable methods for producing catalyst fines are described inU.S. Pat. Nos. 6,030,915 and 6,127,229, each of which is incorporatedherein by reference in its entirety. In some instances, catalyst finesmay be intentionally removed from a solid catalyst production run, sincethey may be difficult to sequester in some catalytic processes.Techniques for removing catalyst fines from larger catalyst solids mayinclude, for example, sieving or like size separation processes. Whenconducting in situ catalytic reduction reaction processes, such as thosedescribed herein, catalyst fines may be particularly well suited, sincethey can be easily fluidized and distributed in the interstitial porespace of the digesting cellulosic biomass solids.

Catalysts that are not particularly poison-tolerant may also be used inconjunction with the techniques described herein. Such catalysts mayinclude, for example, Ru, Pt, Pd, or compounds thereof disposed on asolid support such as, for example, Ru on titanium dioxide or Ru oncarbon. Although such catalysts may not have particular poisontolerance, they may be regenerable, such as through exposure of thecatalyst to water at elevated temperatures, which may be in either asubcritical state or a supercritical state.

The catalysts used in conjunction with the processes described hereinmay be operable to generate molecular hydrogen. For example, in someembodiments, catalysts suitable for aqueous phase reforming (i.e., APRcatalysts) may be used. Suitable APR catalysts may include, for example,catalysts comprising Pt, Pd, Ru, Ni, Co, or other Group VIII metalsalloyed or modified with Re, Mo, Sn, or other metals. Thus, in someembodiments described herein, an external hydrogen feed may not beneeded in order to effectively carry out the stabilization of solublecarbohydrates by a catalytic reduction reaction. However, in otherembodiments, an external hydrogen feed may be used, optionally incombination with internally generated hydrogen. In yet otherembodiments, the molecular hydrogen needed may be externally supplied tothe cellulosic biomass solids or the molecular hydrogen may beinternally generated hydrogen. If external hydrogen is provided, themolecular hydrogen may be supplied as an upwardly directed fluid stream.Benefits of supplying an upwardly directed fluid stream are describedherein.

The digestion solvent provided to the first reaction zone may comprisean organic solvent. In various embodiments, the digestion solvent maycomprise an organic solvent and water. Although any organic solvent thatis at least partially miscible with water may be used in the digestionsolvent, particularly advantageous organic solvents are those that canbe directly converted into fuel blends and other materials without beingseparated from the alcoholic component. That is, particularlyadvantageous organic solvents are those that may be co-processed duringdownstream further processing reactions with the alcoholic componentbeing produced. Suitable organic solvents in this regard may include,for example, ethanol, ethylene glycol, propylene glycol, glycerol,phenolics, and any combination thereof. Other suitable organic solventsmay include sugar alcohols, for example.

In an embodiment, the organic solvent may comprise a glycol or betransformable to a glycol under the conditions used for stabilizingsoluble carbohydrates. In some embodiments, the digestion solvent maycomprise water and glycerol. Glycerol may be a particularly advantageousorganic solvent in this regard, since it comprises a good solvent forsoluble carbohydrates and readily undergoes a catalytic reductionreaction to form a glycol in the presence of molecular hydrogen and asuitable catalyst. In addition, glycerol is inexpensive and is readilyavailable from natural sources. Thus, in some embodiments, the methodsdescribed herein may comprise co-processing a glycol formed from anorganic solvent, particularly glycerol, in conjunction with a glycolformed from soluble carbohydrates.

In some embodiments, the digestion solvent may further comprise a smallamount of a monohydric alcohol. The presence of at least some monohydricalcohols in the digestion solvent may desirably enhance the digestionand/or the catalytic reduction reactions being conducted therein. Forexample, inclusion of about 1% to about 5% by weight monohydric alcoholsin the digestion solvent may desirably maintain catalyst activity due toa surface cleaning effect. At higher concentrations of monohydricalcohols, bulk solvent effects may begin to predominate. In someembodiments, the digestion solvent may comprise about 10 wt. % or lessmonohydric alcohols, with the balance of the digestion solventcomprising water and another organic solvent. In some embodiments, thedigestion solvent may comprise about 5 wt. % or less monohydricalcohols, or about 4% or less monohydric alcohols, or about 3% or lessmonohydric alcohols, or about 2% of less monohydric alcohols, or about1% or less monohydric alcohols. Monohydric alcohols present in thedigestion solvent may arise from any source. In some embodiments, themonohydric alcohols may be formed as a co-product with the alcoholiccomponent being formed by the catalytic reduction reaction. In some orother embodiments, the monohydric alcohols may be formed by a subsequentcatalytic reduction of the initially produced alcoholic component andthereafter returned to the cellulosic biomass solids. In still otherembodiments, the monohydric alcohols may be sourced from an externalfeed that is in flow communication with the cellulosic biomass solids.

In some embodiments, the digestion solvent may comprise between about 1%water and about 99% water, with the organic solvent comprising thebalance of the digestion solvent composition. Although higherpercentages of water may be more favorable from an environmentalstandpoint, higher quantities of organic solvent may more effectivelypromote hydrothermal digestion due to the organic solvent's greaterpropensity to solubilize carbohydrates and promote catalytic reductionof the soluble carbohydrates. In some embodiments, the digestion solventmay comprise about 90% or less water by weight. In other embodiments,the digestion solvent may comprise about 80% or less water by weight, orabout 70% or less water by weight, or about 60% or less water by weight,or about 50% or less water by weight, or about 40% or less water byweight, or about 30% or less water by weight, or about 20% or less waterby weight, or about 10% or less water by weight, or about 5% or lesswater by weight.

Various illustrative embodiments of the biomass conversion methods andsystems described herein will now be further described with reference tothe drawings. When like elements are used in one or more figures,identical reference characters will be used in each figure, and adetailed description of the element will be provided only at its firstoccurrence. Some features of the biomass conversion systems may beomitted in certain depicted configurations in the interest of clarity.Moreover, certain features such as, but not limited to pumps, valves,gas bleeds, gas inlets, material (such as fluids) inlets, materialoutlets and the like have not necessarily been depicted in the figures,but their presence and function will be understood by one havingordinary skill in the art. In the figures, arrows have been drawn todepict the direction of material flow (such as liquid or gas).

FIGS. 1-3 depict biomass processing system 1. A first reaction contentis provided to a reactor in a first reaction zone, where the reactor ishydrothermal digestion unit 2 and the reaction zone is not depicted. Thefirst reaction content comprises cellulosic biomass, a catalyst capableof activating molecular hydrogen, a digestion solvent, and molecularhydrogen. The first reaction content subsequent to the initial materialsprovided to hydrothermal digestion unit 2 can also comprise a phenolicsportion, which will be further discussed below, where the phenolicsportion can serve as part of the digestion solvent. While FIGS. 1-3shows one hydrothermal digestion unit 2 in the first reaction zone, itis understood that the first reaction zone can comprise any suitablenumber of hydrothermal digestion unit coupled to one another (e.g., influid communication with one another), such as at least two, three,four, five, six, or more hydrothermal digestion units. The catalystcapable of activating molecular hydrogen provided to hydrothermaldigestion unit 2 preferably comprises fluidly mobile catalyst particles10. For instance, hydrothermal digestion unit 2 can be a slurry reactoror an ebullating bed reactor. In the interest of clarity, the cellulosicbiomass, digestion solvent, and molecular hydrogen in hydrothermaldigestion unit 2 have not been depicted. If the first reaction zone hasmore than one hydrothermal digestion units, these units can be anycombination of a slurry reactor and an ebullating bed reactor. Forinstance, all hydrothermal digestion units can be slurry reactors, allhydrothermal digestion units can be ebullating bed reactors, or thehydrothermal digestion units can be any combination of slurry andebullating bed reactors.

The reaction content in hydrothermal digestion unit 2 is heated to forma first reaction product comprising phenolics and an alcoholiccomponent. The phenolics is derived from lignin in the cellulosicbiomass, and the alcoholic component is formed from solublecarbohydrates derived from cellulosic biomass. Heating of the firstreaction content provides for in situ catalytic reduction wheredigestion of the cellulosic biomass and catalytic reduction of solublecarbohydrates takes place in the same reactor. The reaction content inhydrothermal digestion unit 2 is heated to a temperature that may be ina range of about 190 to 260 degrees C., such as in a range of about 225to 245 degrees C. For instance, the reaction content in hydrothermaldigestion unit 2 can be heated to about 190, 195, 200, 205, 210, 215,220, 225, 230, 235, 240, 245, 250, 255, or 260 degrees C.

The heating of the first reaction content in hydrothermal digestion unit2 is preferably performed under a pressurized state. As used herein, theterm “pressurized state” refers to a pressure that is greater thanatmospheric pressure (1 bar). For example, hydrothermal digestion unit 2may have a pressure of at least about 30 bar, such as at least about 45bar, at least about 60 bar, at least about 75 bar, at least about 90bar, at least about 100 bar, at least about 110 bar, at least about 120bar, or at least about 130. Hydrothermal digestion unit 2 may have apressure of at most about 450 bar, such as at most about 330 bar, atmost about 200 bar, at most about 175 bar, at most about 150 bar, or atmost about 130 bar. As such, hydrothermal digestion unit 2 may have apressure in a range of about 30 to 450 bar, such as a range of about 45and 330 bar or in a range of about 75 to 130 bar. Hydrogen is preferablyused to achieve the desired total pressure of hydrothermal digestionunit 2. For instance, hydrogen partial pressure of greater than 5 bar,greater than 10, or greater than 25 bar can be provided to hydrothermaldigestion unit 2 to achieve the desired total pressure. Heating of thedigestion solvent in hydrothermal digestion unit 2 in a pressurizedstate may allow the normal boiling point of the digestion solvent to beexceeded, thereby allowing the rate of hydrothermal digestion to beincreased relative to lower temperature digestion processes.

The first reaction content in hydrothermal digestion unit 2 may have apH in a range of about 3 to 12, such as 4 to 8 or 5 to 7. As such, thecontent of hydrothermal digestion unit 2 may have a pH that allows forcatalytic reduction reaction to take place.

The reaction content in hydrothermal digestion unit 2 may be heated forat least 30 minutes and up to 10 hours, such as 120 minutes to 300minutes. For example, digestion may be carried out for at least 30minutes, at least 60 minutes, at least 120 minutes, at least 180minutes, at least 240 minutes, at least 300 minutes, at least 360minutes, at least 420 minutes, at least 480 minutes, at least 540minutes, or at least 600 minutes. Digestion may be carried out at most600 minutes, at most 540 minutes, at most 480 minutes, at most 420minutes, at most 360 minutes, at most 300 minutes, at most 240 minutes,at most 180 minutes, at most 120 minutes, at most 60 minutes, or at most30 minutes.

Referring to FIGS. 1-3, hydrothermal digestion unit 2 may be chargedwith a fixed amount of catalyst particulates 10, while cellulosicbiomass solids are continuously or semi-continuously added thereto,thereby allowing hydrothermal digestion to take place in a continualmanner. Cellulosic biomass may be introduced to hydrothermal digestionunit 2 in the first reaction zone via solids introduction mechanism 4.As used herein, the term “continuous addition” and grammaticalequivalents thereof will refer to a process in which cellulosic biomasssolids are added to a hydrothermal digestion unit in an uninterruptedmanner without fully depressurizing the hydrothermal digestion unit. Asused herein, the term “semi-continuous addition” and grammaticalequivalents thereof will refer to a discontinuous, but as-needed,addition of cellulosic biomass solids to a hydrothermal digestion unitwithout fully depressurizing the hydrothermal digestion unit. That is,fresh cellulosic biomass solids may be added to hydrothermal digestionunit 2 on a continual or an as-needed basis in order to replenishcellulosic biomass solids that have been digested to form solublecarbohydrates.

Solids introduction mechanism 4 may comprise loading mechanism 6 andpressure transition zone 8, which may elevate the cellulosic biomassfrom atmospheric pressure to a pressure near that of the operatingpressure of hydrothermal digestion unit 2, particularly whenhydrothermal digestion unit 2 is in a pressurized state. This allows forcontinuous or semi-continuous introduction of cellulosic biomass to takeplace without fully depressurizing hydrothermal digestion unit 2. Thatis, the cellulosic biomass solids may be continuously orsemi-continuously added to the hydrothermal digestion unit while thehydrothermal digestion unit is in a pressurized state. Without theability to introduce fresh cellulosic biomass to a pressurizedhydrothermal digestion unit, depressurization and cooling of thehydrothermal digestion unit may take place during biomass addition,significantly reducing the energy- and cost-efficiency of the biomassconversion process.

Pressure transition zone 8 may comprise one or more suitablepressurization zones for pressurizing and introducing cellulosic biomasssolids to hydrothermal digestion unit 2. Such suitable pressurizationzones are described in more detail in commonly owned United StatesPatent Application Publications 2013/0152457 and 2013/0152458, andincorporated herein by reference in their entirety. Suitablepressurization zones described therein may include, for example,pressure vessels, pressurized screw feeders, and the like. Multiplepressurization zones may be connected in series to increase the pressureof the cellulosic biomass solids in a stepwise manner.

In various embodiments, soluble carbohydrates produced from cellulosicbiomass solids may be converted into a reaction product comprising aglycol via a catalytic reduction reaction mediated by a catalyst that iscapable of activating molecular hydrogen. As described in commonly ownedU.S. Patent Applications 61/720,704 and 61/720,714, entitled “Methodsfor Production and Processing of a Glycol Reaction Product Obtained fromHydrothermal Digestion of Cellulosic Biomass Solids” and “Methods forConversion of a Glycol Reaction Product Obtained from HydrothermalDigestion of Cellulosic Biomass Solids Into a Dried Monohydric AlcoholFeed,” each filed Oct. 31, 2012 and incorporated herein by reference inits entirety, production of glycols may present several processadvantages, particularly with regard to downstream further processingreactions. In other aspects, formation of monohydric alcohols may bemore desirable.

Referring to FIGS. 1-3, catalyst particulates 10 are capable ofactivating molecular hydrogen. At least a portion of catalystparticulates 10 may be distributed in the cellulosic biomass,particularly in hydrothermal digestion unit 2. If in situ catalyticreduction is carried out, effective distribution of catalystparticulates 10 throughout cellulosic biomass solids for in situcatalytic reduction reaction is desired. This may be achieved by usingfluid flow to convey catalyst particulates 10 into the interstitialspaces within a charge of cellulosic biomass solids. As used herein, theterms “distribute,” “distribution,” and variants thereof refer to acondition in which catalyst particulates are present at all heights of acharge of cellulosic biomass. No particular degree of distribution isimplied by use of the term “distribute” or its variants. Catalystdistribution may comprise a substantially homogeneous distribution, suchthat a concentration of catalyst particulates is substantially the sameat all heights of a cellulosic biomass charge. Catalyst distribution maycomprise a heterogeneous distribution, such that differentconcentrations of catalyst particulates are present at various heightsof the cellulosic biomass charge. When a heterogeneous distribution ofcatalyst particulates is present, a concentration of catalystparticulates in the cellulosic biomass solids in hydrothermal digestionunit 2 may increase from top to bottom or decrease from top to bottom.In some embodiments, a heterogeneous distribution may comprise anirregular concentration gradient.

Catalyst particulates 10 may be conveyed into the cellulosic biomasssolids in hydrothermal digestion unit 2 for distribution using fluidflow from any direction. In particular, at least a portion of catalystparticulates 10 may be conveyed by upwardly directed fluid flow, or atleast that upwardly directed fluid flow be present. For instance,catalyst particulates 10 may be supplied through fluid inlet line 9 asshown in FIGS. 1-3. Such upwardly directed fluid flow may promoteexpansion of the cellulosic biomass solids and disfavor gravity-inducedcompaction that occurs during their addition and digestion. In addition,when upwardly directed fluid flow is present, there may be a reducedneed to utilize mechanical stirring or like mechanical agitationtechniques that might otherwise be needed to obtain an adequate catalystdistribution.

Suitable techniques for using fluid flow to distribute catalystparticulates 10 within cellulosic biomass solids are described incommonly owned U.S. Patent Applications 61/665,727 and 61/665,627, eachfiled on Jun. 28, 2012 (PCT/US2013/048239 and PCT/US2013/048248) andincorporated herein by reference in its entirety. As described therein,cellulosic biomass solids may have at least some innate propensity forretaining catalyst particulates 10 being conveyed by fluid flow, and atleast a portion of the cellulosic biomass solids may be sized to betterpromote such retention. In addition, using fluid flow, particularlyupwardly directed fluid flow, to force catalyst particulates 10 toactively circulate through a charge of digesting cellulosic biomasssolids may ensure adequate catalyst distribution as well asadvantageously reduce thermal gradients that may occur duringhydrothermal digestion. As a further advantage, active circulation ofcatalyst particulates 10 may address the problem created by theproduction of cellulosic biomass fines, since they may be co-circulatedwith catalyst particulates for continued digestion to take place inhydrothermal digestion unit 2.

The upwardly directed fluid flow may comprise a gas stream, a liquidstream, or any combination thereof. Also, the upwardly directed fluidflow may comprise one upwardly directed fluid stream, or two upwardlydirected fluid streams, or three upwardly directed fluid streams, orfour upwardly directed fluid streams, or five upwardly directed fluidstreams.

At least some of the one or more upwardly directed fluid streams maycontain catalyst particulates at its source. That is, the fluidstream(s) may comprise a stream of catalyst particulates. The one ormore upwardly directed fluid streams may convey catalyst particulatestherein. In other circumstances, the one or more upwardly directed fluidstreams may not contain catalyst particulates at its source, but theymay still fluidize catalyst particulates located in or near thecellulosic biomass solids.

The one or more upwardly directed fluid streams may comprise a gasstream. For example, a gas stream being used for upwardly directed fluidflow may comprise a stream of molecular hydrogen. Steam, or an inert gassuch as nitrogen, for example, may be used in place of or in addition toa stream of molecular hydrogen. Up to about 40% steam may be present inthe fluid stream.

The one or more upwardly directed fluid streams may comprise a liquidstream, particularly when it is not necessarily desired to maintaincatalyst particulates in the cellulosic biomass solids and/or a gasstream alone is insufficient to distribute catalyst particulates, forexample. Unlike a gas stream, a liquid stream may convey catalystparticulates through the cellulosic biomass solids, add to the liquidhead surrounding the cellulosic biomass solids, and eventually spillover. In other circumstances, catalyst fluidization may be incomplete,and a liquid stream may still not convey catalyst particulatescompletely through the cellulosic biomass solids before the liquid headspills over.

As such, in certain instances, at least a portion of the liquid head maybe circulated through the cellulosic biomass solids. Suitablehydrothermal digestion units configured for circulating a liquid phasetherethrough, such as hydrothermal digestion unit 2 depicted in FIG. 1,are described in commonly owned U.S. Patent Application 61/665,717,filed on Jun. 28, 2012 (PCT/US2013/048212) and incorporated herein byreference in its entirety. Specifically, hydrothermal digestion unit 2may comprise a fluid circulation loop through which the liquid phase andoptionally catalyst particulates 10 are circulated for distribution inthe cellulosic biomass solids.

Another way to distribute catalyst particulates 10 is to convey at leasta portion comprising phenolics of the content of hydrothermal digestionunit 2 to a point above at least a portion of the cellulosic biomasssolids and release that portion. Because catalyst particulates 10 canhave the tendency to accumulate around phenolics, particularly if thephenolics aggregate to form a phenolics liquid phase, providing thisphenolics potion above cellulosic biomass solids in hydrothermaldigestion unit 2 can act to release catalyst particulates for downwardpercolation through the cellulosic biomass solids. Techniques fordownward percolation of catalyst particulates and phenolics aredescribed in commonly owned U.S. Patent Application 61/720,757 filedOct. 31, 2012, entitled “Methods and Systems for Distributing a SlurryCatalyst in Cellulosic Biomass Solids” and U.S. Patent Publication No.20140174432, filed on Dec. 17, 2013, the disclosures of which areincorporated herein by reference in their entirety.

As shown in FIGS. 1-3, the first reaction product formed by heating thefirst reaction content in hydrothermal digestion unit 2 may be conveyedvia line 12 to a reactor in a second reaction zone, which is phenolicsconversion unit 16. While FIGS. 1-3 shows one phenolics conversion unit16 in the first reaction zone, it is understood that the second reactionzone can comprise any suitable number of reactors coupled to oneanother, such as at least two, three, four, five, six, or more phenolicsconversion units.

In FIGS. 1-3, the first reaction product is part of a second reactioncontent that is provided to phenolics conversion unit 16. The secondreaction content further comprises catalyst capable of activatingmolecular hydrogen, and molecular hydrogen. The second reaction contentsubsequent to the initial materials provided to phenolics conversionunit 16 can also comprise a phenolics portion, which will be furtherdiscussed below. The second reaction content is heated in phenolicsconversion unit 16 to form a second reaction product comprisingunconverted phenolics, hydrocarbons converted from phenolics.Optionally, the second reaction product can also comprise monohydricalcohols converted from triols and glycol in the alcoholic component inthe first reaction product.

Referring to FIG. 1, the first reaction product may be provided tophenolics conversion unit 16 without passing through any catalystremoval mechanism, as compared to FIGS. 2 or 3, where catalyst removalunit 17 is employed. As such, at least some catalyst particulates 10 maybe accumulated in the first reaction product coming to phenolicsconversion unit 16, particularly when hydrothermal digestion unit 2 is aslurry reactor. As such, when catalyst is not removed the first reactionproduct, such as that shown in FIG. 1, the catalyst capable ofactivating molecular hydrogen provided to phenolics conversion unit 16preferably also comprises fluidly mobile catalyst particles. Forinstance, phenolics conversion unit 16 can be a slurry reactor or anebullating bed reactor. If the second reaction zone has more than onephenolics conversion units, these units can be any combination of aslurry reactor or an ebullating bed reactor. For instance, all phenolicconversion units can be slurry reactors, all phenolic conversion unitscan be ebullating bed reactors, or the phenolic conversion units can bea combination of slurry and ebullating bed reactors. The methods fordistributing catalyst particles described above with respect tohydrothermal digestion unit 2 are also applicable for distributingcatalyst particles through the second reaction content in phenolicsconversion unit 16.

In FIG. 1, both the reactor(s) in the first reaction zone, e.g.,hydrothermal digestion unit 2, and the reactor(s) in the seconddigestion zone, e.g., phenolics conversion unit 16, may all use the samefluidly mobile catalyst particles, such as slurry reactors or ebullatingbed reactors. For example, hydrothermal digestion unit 2 and phenolicsconversion unit 16 may both be slurry reactors. Hydrothermal digestionunit 2 and phenolics conversion unit 16 may both be ebullating bedreactors.

In FIG. 1, The reactor(s) in the first reaction zone, e.g., hydrothermaldigestion unit 2, and the reactor(s) in the second reaction zone, e.g.,phenolics conversion unit 16, may be reactors using different fluidlymobile catalyst particles, such as any combination of at least oneslurry reactor and at least one ebullating bed reactor. For example,hydrothermal digestion unit 2 may be a slurry reactor and phenolicsconversion unit 16 may be an ebullating bed reactor, or vice versa.

The catalyst provided to phenolics conversion unit 16 can comprisecatalyst particles 10 in the first reaction product coming fromhydrothermal digestion unit 2, particularly when hydrothermal digestionunit 2 is a slurry reactor. That is, providing the first reactionproduct to phenolics conversion product 16 can also provide the catalystcapable of activating molecular hydrogen for the second reactioncontent. Fresh catalyst may or may not be provided to phenolicsconversion unit 16. Additional catalyst may also be provided tophenolics conversion unit 16 to supplement catalyst particles 10 fromhydrothermal digestion unit 2, if desired. The composition of theadditional catalyst provided to phenolics conversion unit 16 can bedifferent from the composition of catalyst particles 10, particularly ifphenolics conversion unit 16 is an ebullating bed reactor. Catalystprovided to phenolics conversion unit 16 can comprise material(s) thatis optimized for hydrogen generation, meaning a criteria for selectionof the catalyst material(s) for phenolics conversion unit 16 is relativeyields of molecular hydrogen.

FIG. 2 is similar to FIG. 1, except that system 1 now includes catalystremoval unit 17 to remove catalyst particulates 10, if any, in the firstreaction product before it is routed phenolics conversion unit 16,particularly when hydrothermal digestion unit 2 is a slurry reactor.Removal of catalyst particulates 10 may take place by any techniqueknown to one having ordinary skill in the art and may include, forexample, filtration, centrifugation, hydroclone separation, settling,any combination thereof, and the like. That is, catalyst removal unit 17may comprise any suitable equipment for the selected technique toremoval catalyst known to one having ordinary skill in the art. In FIG.2, the first reaction product is routed to catalyst removal unit 17 vialine 12. After catalyst removal, the first reaction product can continueon to phenolics conversion unit 16 via line 34. The removed catalystparticles can be provided to hydrothermal digestion unit 2 via line 28for further use as a digestion solvent. As such, during operation ofsystem 1, the first reaction content provided to hydrothermal digestionunit 2 can also comprise recycled catalyst particles 10 coming fromcatalyst removal unit 17.

Return of catalyst particulates 10 may occur continuously or in batchmode. Fluid flow may be used to return catalyst particulates 10 to thecellulosic biomass solids. For example, catalyst particulates 10 may becarried by a stream of the digestion solvent provided to hydrothermaldigestion unit 2, a stream of the portion of the unconverted phenolicsrouted back to hydrothermal digestion unit 2, or any combinationthereof. Catalyst particulates 10 may be at least partially regeneratedafter being removed from the first reaction product. Regeneration may bedesirable if the catalytic activity is not sufficiently high, forexample. Hydrothermal reaction in phenolics conversion unit 16 can alsoprovide regeneration of the catalyst.

FIG. 3 also includes catalyst removal unit 17 and additionally providesan illustrative way to reduce the volume of the first reaction productthat is subject to catalyst removal. FIG. 3 is similar to FIG. 2 exceptthat as shown in FIG. 3, the first reaction product may be routed firstto flasher 30, via line 12, before going to catalyst removal unit 17.Flasher 30 provides an overhead fraction from the first reactionproduct, where the overhead fraction comprises compounds that arelighter than water, e.g., compounds with a normal boiling point of lessthan 100 degrees C. Non-limiting illustrative compounds lighter thanwater include hydrogen, carbon dioxide, and light alcohols, includingmethanol and ethanol. The overhead fraction preferably comprisescompounds lighter than water in an amount of at least 2%, at least 5%,at least 10%, or at least 25% by weight based on the total weight of thefirst reaction product. The remaining portion of the first reactionproduct exiting flasher 30 is a bottoms fraction that is now reduced involume as compared to the first reaction product in line 12. Flasher 30can be any suitable flasher known to one of ordinary skill in the artthat can provide an overhead fraction and a bottoms fraction asdescribed. For instance, a suitable flasher can apply heat and/orpressure to obtain the desired overhead fraction and bottoms fraction.

At least a portion of the overhead fraction can be provided via line 13to phenolics conversion unit 16 and/or it can be provided via line 25 toseparation zone 20 and/or it can be optionally provided directly tofurther processing zone 22 (not shown). The bottoms fraction can berouted via line 32 to catalyst removal unit 17. The reduced volumeprovided to catalyst removal unit 17 via line 32 in FIG. 3 relative tothe volume provided by line 12 in FIG. 2 can increase catalyst removalefficiency of unit 17, particularly if it employs a filter mechanism.This is because filter mechanisms generally are not as efficient whenfiltering a multiphase mixture versus a single phase mixture. As such,flasher 30 can provide a bottoms fraction that has at least a portion ofthe vapor phase removed in the overhead fraction. The bottoms fractionwith the catalyst removed can be provided to phenolics conversion unit16 via line 21. As shown in FIG. 3, at least a portion of the overheadfraction from flasher 30 and bottoms fraction after catalyst removalfrom unit 17 can be combined then provided to phenolics conversion unit16. Alternatively or additionally, they can be individually provided tophenolics conversion unit 16.

Like FIG. 1, in FIGS. 2 and 3, the reactor(s) in the first reactionzone, e.g., hydrothermal digestion unit 2, and the reactor(s) in thesecond digestion zone, e.g., phenolics conversion unit 16, may all usethe same fluidly mobile catalyst particles or they may use differentfluidly mobile catalyst particles as described above. Unlike FIG. 1,catalyst removal such as that provided by catalyst removal unit 17 inFIGS. 2 and 3 can allow for a reactor in the second reaction zone, e.g.,phenolics conversion unit 16, to use a catalyst that does not comprisefluidly mobile catalyst particulates, such as a fixed bed and tricklebed reactor. As such, in addition to the reactors arrangement availableas described in FIG. 1 with respect to fluidly mobile catalystparticulates, FIGS. 2 and 3 also provide for reactor(s) in the firstreaction zone, e.g., hydrothermal digestion unit 2, can be at least oneof a slurry reactor and an ebullating bed catalyst, and reactor(s) inthe second reaction zone, e.g., phenolics conversion unit 16, can be atleast one of a fixed bed reactor and a trickle bed reactor. Additionallyor alternatively, this may be achieved by employing an ebullating bedreactor in the first reaction zone coupled to a fixed bed or trickle bedreactor in the second reaction zone.

Referring to FIG. 2 or FIG. 3, inclusion of catalyst removal unit 17allows for selection of a catalyst for hydrothermal digestion unit 2 andphenolics conversion unit 16 to be based on different properties. Forinstance, the catalyst for unit 2 can be selected at least based onproperties that would make it suitable or optimal for in situ catalyticreduction. Similarly, the catalyst for unit 16 can be selected at leastbased on properties that would make it suitable or optimal forconversion of phenolics to hydrocarbons and optionally, of triol orglycol to monohydric alcohol.

Accordingly, if the second reaction zone has more than one phenolicsconversion unit 16, these units can be any combination of a fixed bedreactor, a trickle bed reactor, a slurry reactor, or an ebullating bedreactor. For instance, all phenolics conversion units can be fixed bedreactors, all phenolics conversion units can be trickle bed reactors,all phenolics conversion units can be slurry reactors, all phenolicsconversion units can be ebullating bed reactors, or the phenolicsconversion units can be a combination of a fixed bed reactor, a tricklebed reactor, a slurry reactor, and/or an ebullating bed reactor. If thesecond reaction zone of a system described herein has a phenolicsconversion unit that is a fixed bed reactor or a trickle bed reactor,the system can employ a configuration and/or mechanism that minimizescatalyst particulates from a hydrothermal digestion unit entering thephenolics conversion unit that is a fixed bed or trickle bed reactor. Anillustrative mechanism can be catalyst removal unit 17 as described inFIG. 2 or FIG. 3. An illustrative configuration can be providing a firstreaction product coming from a hydrothermal digester unit that is anebullating bed reactor.

Referring to FIGS. 1-3, in addition to providing conversion ofhydrocarbons from phenolics, phenolics conversion unit 16 may also beconfigured to generate molecular hydrogen. For example, under certaincircumstances, phenolics conversion unit 16 can be operated atintensified catalyst concentration as compared to hydrothermal digestionunit 2, which leads to generation of more hydrogen. One instance wherethis can be achieved is when both hydrothermal digestion unit 2 andphenolics conversion unit 16 are slurry reactors and phenolicsconversion unit 16 has a smaller reactor volume. When the first reactionproduct with catalyst particulates accumulated therein is provided tophenolics conversion unit 16, there would be a higher or intensifiedactivity because of the higher catalyst concentration due to thereduction in reactor volume. As such, the reduction in reactor volumesize can provide for higher catalyst activity per reactor unit volumeand thus lower reactor cost. Another instance is adding fresh catalystto increase the catalyst concentration to intensify the catalyticactivity. As mentioned, the fresh catalyst added to phenolics conversionunit 16 can have the same composition as that of the catalyst inhydrothermal digestion unit 2 and/or it can have a differentcomposition, particularly materials that can facilitate or enhancehydrogen generation. Additionally or alternately, phenolics conversionunit 16 can be operated at a pressure that is lower than a pressure ofhydrothermal digestion unit 2. The lower pressure differential inphenolics conversion unit 16 drives the reaction to generate molecularhydrogen. Phenolics conversion unit 16 can have a pressure that is 5 to15 bar lower than a pressure in hydrothermal digestion unit 2. Inparticular, phenolics conversion unit 16 can have a pressure of lowerthan 200 bar. Accordingly, by configuring phenolics conversion unit 16to generate molecular hydrogen, it is possible to generate some or allthe molecular hydrogen needed by a system described herein in phenolicsconversion unit 16, allowing for the option of eliminating the need toimport hydrogen derived from other sources.

Referring to FIGS. 1-3, heating of the second reaction content inphenolics conversion unit 16 hydrotreat compounds in the first reactionproduct that are hydrotreatable but had not been hydrotreated inhydrothermal digestion unit 2. In particular, heating of the secondreaction content provides for conversion of at least a portion of thephenolics in phenolics conversion unit 16 to hydrocarbons, andoptionally, conversion of at least a portion of triol and glycol tomonohydric alcohol. The reaction content in phenolics conversion unit 16is heated to a temperature that may be in a range of about 210 to 300degrees C., such as in a range of 270 to 290 degrees C. or at least 270degrees C. For instance, the reaction content in phenolics conversionunit can be heated to about 210, 215, 220, 225, 230, 235, 240, 245, 250,255, 260, 265, 270, 275, 280, 285, 290, 295, or 300 degrees C. In aparticular embodiment, a temperature of the second reaction product atan outlet of phenolics conversion unit 16 is greater than a temperatureof the first reaction product at an outlet of hydrothermal digestionunit 2. The hydrotreating of the second reaction content in phenolicsconversion unit 16 can also provide for regeneration of catalystparticulates accumulated in the first reaction product, if they arepresent.

In FIGS. 1-3, phenolics conversion unit 16 is preferably in apressurized state. For example, phenolics conversion unit 16 may have apressure of at least about 30 bar, such as at least about 45 bar, atleast about 60 bar, at least about 75 bar, at least about 90 bar, atleast about 100 bar, at least about 110 bar, at least about 120 bar, orat least about 130. Phenolics conversion unit 16 may have a pressure ofat most about 450 bar, such as at most about 330 bar, at most about 200bar, at most about 175 bar, at most about 150 bar, or at most about 130bar. As such, phenolics conversion unit 16 may have a pressure in arange of about 30 to 450 bar, such as a range of about 45 and 330 bar orin a range of about 75 to 130 bar. Hydrogen is preferably used toachieve the desired total pressure of phenolics conversion unit 16. Forinstance, hydrogen partial pressure of greater than 5 bar, greater than10, or greater than 25 bar can be provided to phenolics conversion unit16 to achieve the desired total pressure.

Referring to FIGS. 1-3, the reaction content in phenolics conversionunit 16 may be heated for at least 30 minutes and up to 10 hours, suchas 120 minutes to 300 minutes. For example, digestion may be carried outfor at least 30 minutes, at least 60 minutes, at least 120 minutes, atleast 180 minutes, at least 240 minutes, at least 300 minutes, at least360 minutes, at least 420 minutes, at least 480 minutes, at least 540minutes, or at least 600 minutes. Digestion may be carried out at most600 minutes, at most 540 minutes, at most 480 minutes, at most 420minutes, at most 360 minutes, at most 300 minutes, at most 240 minutes,at most 180 minutes, at most 120 minutes, at most 60 minutes, or at most30 minutes.

The hydrothermal reaction carried out in phenolics conversion unit 16can provide for conversion of lignin-derived phenolics into desirablehydrocarbons that can be used in a fuel blends, such as gasoline.Illustrative, non-limiting hydrocarbon compounds include alkanes,alkenes, cycloalkanes and their alkyl substituents or derivatives, andcycloalkenes and their alkyl substituents or derivatives, which can besuitable for use in fuel composition, for instance gasoline or diesel.For instance, illustrative hydrocarbon compounds can include but are notlimited to cyclohexane, cyclohexene, propyl cyclopentane, propylcyclopentene, propyl cyclohexane, propyl cyclohexene, anisole, propylbenzene, cyclohexanone, methyl cyclohexanone, and methyl propyl benzene.The conversion of lignin derived phenolics into desirable hydrocarbonsmay not be complete, which can leave unconverted phenolics stillremaining in the second reaction product. Optionally, the hydrothermalreaction carried out in phenolics conversion unit 16 can also providefor hydrodeoxygenation where triols and glycol of the alcoholiccomponent are converted to monohydric alcohol. The hydrodeoxygenationmay not be complete, which can leave triols and glycol still remainingin the second reaction product. As such, the second reaction product cancomprise unconverted phenolics, hydrocarbons converted from phenolics,and at least a portion of the alcoholic component.

Referring to FIGS. 1-3, phenolics conversion unit 16 can also beoperated at conditions that are suitable or optimal for generation ofmolecular hydrogen. In general, if phenolics conversion unit 16 isoperated at a higher temperature than hydrothermal digestion unit 2,there is a tendency for the reaction in phenolics conversion unit 16 togenerate more molecular hydrogen. Keeping the total pressure ofphenolics conversion unit 16 below 200 bar can allow for more molecularhydrogen generation as compared to if phenolics conversion unit 16 has atotal pressure of greater than 200 bar, particularly when hydrogen isused to achieve the pressure of greater than 200 bar.

Methanol can also be generated when heating the first reaction productto a temperature of at least about 250° C. Without being bound by anytheory or mechanism, it is believed that the methanol formation occurreddue to cleavage of at least some of the phenolic methyl ethers on thelignin polymer backbone. The methanol, which is a monohydric alcohol,may be transformed into fuel blends and other materials throughdownstream further processing reactions, such as those that take placein further processing zone 22 discussed further below.

Referring to FIGS. 1-3, the second reaction product formed by heatingthe second reaction content in phenolics conversion unit 16 can berouted, via line 18, from phenolics conversion unit 16 in the secondreaction zone to separation zone 20. In separation zone 20, a phenolicsfraction comprising unconverted phenolics is separated from the secondreaction product, which can be provided to a reactor in the firstreaction zone and a reactor in the second reaction zone. The fractioncan be referred to as an unconverted phenolics fraction. The remainingfraction of the second reaction product comprising hydrocarbons andalcoholic component, where the hydrocarbons can be further separatedand/or remain with the alcoholic component for further processing inzone 22. It is understood that the phenolics fraction contain somehydrocarbons and alcoholic component, and vice versa, where theremaining fraction of the second reaction product can comprisephenolics. The difference between the two fractions is that theremaining fraction of the second reaction product contains less than50%, less than 25%, or less than 10% of the total amount of phenolics inthe second reaction product provided to separation zone 20 via line 18.Accordingly, the phenolics fraction contains more than 50%, more than75%, or more than 90% of the total amount of phenolics in the secondreaction product.

Separation zone 20 can comprise any suitable separation mechanism knownto one of ordinary skill in the art to provide the phenolics fractionand the remaining fraction of the second reaction product. For instance,separation zone 20 can comprise a mechanism that separates the compoundsbased on certain properties, such as boiling point and miscibility.Moreover, it is understood that separation zone 20 may comprise morethan one unit and/or stages to achieve the desired separation andfractions. While not shown, glycol in the second reaction product may beseparated and used to increase the glycol content of the digestionsolvent in hydrothermal digestion unit 2.

As mentioned, the hydrothermal reaction in phenolics conversion unit 16hydrotreats compounds that are hydrotreatable, including certainphenolics and alcoholic components, to produce hydrocarbons, such asalkanes and alkenes, and optionally, monohydric alcohol. The furtherhydrotreatment can provide for better separation between unconvertedphenolics and desirable components such as hydrocarbons and monohydricalcohols, which are lighter than the unconverted phenolics. Forinstance, the amount of phenolics that need to be separated downstreamis reduced via conversion to hydrocarbons. Further, the amount of glycoland triols is also reduced via conversion to monohydric alcohols, whichhave boiling points further away from the boiling points of phenolics ascompared to glycol and triols, thereby facilitating separation ofphenolics, at least based on boiling points.

In particular, in FIGS. 1-3, the phenolics fraction is provided tohydrothermal digestion unit 2 via line 11, and it is provided tophenolics conversion unit 16 via line 26. The portion of phenolicsfraction provided to hydrothermal digestion unit 2 in the first reactionzone can serve as a portion of the first reaction content, particularlyas part of the digestion solvent. The portion of phenolics fractionprovided to phenolics conversion unit 16 in the second reaction zone canbe part of the second reaction content, particularly to provideunconverted phenolics for further reversion to hydrocarbons. As such,during operation of system 1, the first reaction content provided tohydrothermal digestion unit 2 and the second reaction content providedto phenolics conversion unit 16 can also comprise recycled unconvertedphenolics in the phenolics fraction coming from separation zone 20.

As shown in FIG. 1, the portion of phenolics fraction provided tophenolics conversion unit 16 in the second reaction zone via line 26 maybe combined with the first reaction product from hydrothermal digestionunit 2 in the first reaction zone provided via line 12 before both enterunit 16. Alternatively, or additionally, the unconverted phenolicscoming from separation zone 20 may be provided to phenolics conversionunit 16 separately from the first reaction product.

As shown in FIG. 2, the portion of phenolics fraction provided tophenolics conversion unit 16 in the second reaction zone via line 26 maybe combined with the first reaction product after catalyst removal byunit 17 provided via line 34 before both enter unit 16. Alternatively,or additionally, the unconverted phenolics coming from separation zone20 may be provided to phenolics conversion unit 16 separately from thefirst reaction product coming from catalyst removal unit 17.

As shown in FIG. 3, the portion of phenolics fraction provided tophenolics conversion unit 16 in the second reaction zone via line 26 maybe combined with at least a portion of the overhead fraction fromflasher 30 provided by line 13 and the bottoms fraction from flasher 30after catalyst removal by unit 17 provided by line 21 before all threeenter unit 16. Alternatively or additionally, at least one of at least aportion of the overhead fraction of the first reaction product, thebottom fraction of the first reaction product after catalyst removal byunit 17, and the phenolics fraction coming from separation zone 20 maybe combined prior to being provided to phenolics conversion unit 16.Alternatively or additionally, these components can be providedindividually to phenolics conversion unit 16.

The at least a portion of the overhead fraction of the first reactionproduct, the bottom fraction of the first reaction product aftercatalyst removal by unit 17, and the phenolics fraction coming fromseparation zone 20 can be provided to phenolics conversion unit 16 inany manner and amount as long as the concentration of phenolics of thesecond reaction content is 50% or less by weight based on the totalweight of the content of the second hydrothermal reaction. Non-limitingillustrative phenolics concentrations of the reaction content in thesecond hydrothermal reaction can be in a range of about 0.1% to 50% byweight, and any amount in between, including less than 45%, less than40%, less than 35%, less than 30%, less than 25%, less than 20%, lessthan 15%, less than 10%, or less than 5% by weight, based on the totalcontent weight of the second hydrothermal reaction.

Referring to FIGS. 1-3, the remaining fraction of the second productreaction comprising hydrocarbons and alcoholic component can beproviding, via line 24, to further processing zone 22, where one or morefurther processing reactions may take place to generate biofuels.Further processing zone 22 can comprise any suitable number of reactorscoupled to one another, such as at least one, two, three, four, five, orsix further processing units. The reaction(s) taking place in furtherprocessing zone 22 can convert the alcoholic component to the desiredhydrocarbon compounds. While not shown, hydrocarbons converted fromphenolics that are in the second reaction product may be separated fromthe second reaction product before it is routed to further processingzone 22, or the hydrocarbons may remain in the second reaction productand go through further processing zone 22 as described herein. Also,hydrogen and water vapor may or may not be removed prior to the furtherprocessing of the remaining fraction.

Optionally, the second reaction product exiting phenolic compoundconversion unit 16 may be optionally subject to a flashing step inseparation zone 20 prior to the remaining fraction entering furtherprocessing zone 22 via line 24. The flashing step may be carried out ata higher pressure than a pressure of further processing zone 22. Forexample, the flashing step may be carried out at a pressure of at leastabout 5 bar, such as greater than 20 bar, greater than 30 bar, greaterthan 4 bar, or greater than 50 bar. Such a flashing step vaporizeshydrocarbons converted from phenolics and alcoholic component andprovides them as vapor to further processing zone 22. To facilitate theflashing, the second reaction product may be optionally heated prior toentering separation zone 20. For instance, the second reaction productmay be provided to separation zone at a temperature of greater than 200degrees C., greater than 300 degrees C., or greater than 400 degrees C.It is understood that separation zone 20 may also be operated at a lowerpressure than further processing zone 22. The flashing and optionalheating of the second reaction product as described can provide forbetter energy integration and efficiency because the compounds routed tofurther processing zone 22 are provided at a pressure that is the sameor higher than the target pressure of further processing zone 22 ascompared to other ways that may involve condensation of the remainingfraction exiting via line 24 and vaporization to provide it to furtherprocessing zone 22 at or above the target pressure.

Referring to FIGS. 1-3, further processing zone 22 may generallycomprise a condensation reaction, often conducted in the presence of acondensation catalyst, in which the alcoholic component or a productformed therefrom is condensed with another molecule to form a highermolecular weight compound. As used herein, the term “condensationreaction” will refer to a chemical transformation in which two or moremolecules are coupled with one another to form a carbon-carbon bond in ahigher molecular weight compound, usually accompanied by the loss of asmall molecule such as water or an alcohol. An illustrative condensationreaction is the Aldol condensation reaction, which will be familiar toone having ordinary skill in the art.

Although a number of different types of catalysts may be used formediating condensation reactions, zeolite catalysts also may beparticularly advantageous in this regard. One zeolite catalyst that maybe particularly well suited for mediating condensation reactions ofalcohols is ZSM-5 (Zeolite Socony Mobil 5), a pentasil aluminosilicatezeolite having a composition of NanAlnSi96-nO192.16H2O (0<n<27), whichmay transform an alcohol feed into a condensation product. Othersuitable zeolite catalysts may include, for example, ZSM-12, ZSM-22,ZSM-23, SAPO-11, and SAPO-41.

In various embodiments, the condensation reaction may take place at atemperature ranging between about 275 degrees C. and about 450 degreesC. The condensation reaction may take place in a condensed phase (e.g.,a liquor phase) or in a vapor phase. For condensation reactions takingplace in a vapor phase, the temperature may range between about 300degrees C. and about 400 degrees C., such as 350 degrees C. or above.The condensation reaction may take place at a pressure in a range ofabout 5 bar to 50 bar, such as 10 bar to 30 bar, including about 15 barto 20 bar.

The alcoholic component, particularly when it includes methanol and anoxygenate, such as such as at least one of ketones, aldehydes, furans,and ethers, can provide for improved conversion of methanol over to afuel compound, such as gasoline or diesel, as compared to otherconventional methanol conversion processes. An example of such aconventional methanol conversion process is the methanol-to-gasolineprocess.

In conventional methanol to gasoline process, methanol is typicallyconverted to gasoline in a two-step process. The first step isdehydrating the methanol to form an equilibrium mixture of dimethylether(DME), methanol, and water. The second step is to pass the mixture overZSM-5 to produce hydrocarbons, water, and a gas phase of lighthydrocarbons. These light hydrocarbons are typically recycled throughthe second step to be combined with the mixture, and the combinedproduct is passed over ZSM-5. If dehydrating is not performed first,then conversion of methanol tend to be heavily weighted to the lighthydrocarbons products and gasoline yield is low. Themethanol-to-gasoline process adjusts for this by recycling the lighthydrocarbons which improves overall gasoline yields.

Unlike the conventional methanol-to-gasoline process, the combination ofmethanol and an oxygenate can help shift the product distribution fromlight hydrocarbons toward higher hydrocarbon compounds yield. Inparticular, the alcoholic component containing methanol and anoxygenate, such as at least one of ketones, aldehydes, furans, andethers, may be converted to a fuels product, such as gasoline, withoutfirst conducting a dehydrating reaction to form dimethylether (DME).

The higher molecular weight compound produced by the condensationreaction may comprise >C₄ hydrocarbons, such as C₄-C₃₀ hydrocarbons,C₄-C₂₄ hydrocarbons, C₄-C₁₈ hydrocarbons, or C₄-C₁₂ hydrocarbons; or >C₆hydrocarbons, such as C₆-C₃₀ hydrocarbons, C₆-C₂₄ hydrocarbons, C₆-C₁₈hydrocarbons, or C₆-C₁₂ hydrocarbons. Consistent with other definitionsprovided, the term “hydrocarbons” refers to compounds containing bothcarbon and hydrogen without reference to other elements that may bepresent, except they do not include a phenolic functional group. Thus,heteroatom-substituted compounds are also described herein by the term“hydrocarbons.” The particular composition of the higher molecularweight compound produced by the condensation reaction may vary dependingon the catalyst(s) and temperatures used for both the catalyticreduction reaction and the condensation reaction, as well as otherparameters such as pressure.

A single catalyst may mediate the transformation of the alcoholiccomponent into a form suitable for undergoing a condensation reaction aswell as mediating the condensation reaction itself. Zeolite catalystsare one type of catalyst suitable for directly converting alcohols tocondensation products in such a manner. A particularly suitable zeolitecatalyst in this regard may be ZSM-5, although other zeolite catalystsmay also be suitable.

On the other hand, a first catalyst may be used to mediate thetransformation of the alcoholic component into a form suitable forundergoing a condensation reaction, and a second catalyst may be used tomediate the condensation reaction. Unless otherwise specified, it is tobe understood that reference herein to a condensation reaction andcondensation catalyst refers to either type of condensation process.Further disclosure of suitable condensation catalysts now follows.Zeolite catalysts may be used as either the first catalyst or the secondcatalyst. Again, a particularly suitable zeolite catalyst in this regardmay be ZSM-5, although other zeolite catalysts may also be suitable.

Various catalytic processes may be used to form higher molecular weightcompounds by a condensation reaction. In some embodiments, the catalystused for mediating a condensation reaction may comprise a basic site, orboth an acidic site and a basic site. Catalysts comprising both anacidic site and a basic site will be referred to herein asmulti-functional catalysts. In some or other embodiments, a catalystused for mediating a condensation reaction may comprise one or moremetal atoms. Any of the condensation catalysts may also optionally bedisposed on a solid support, if desired. Additional details regardingsuitable catalysts are described in commonly owned U.S. patentapplication Ser. No. 14/067,330, filed Oct. 30, 2013, and entitledMethods and Systems for Processing Lignin During Hydrothermal Digestionof Cellulosic Biomass Solids,” the entire disclosure of which isincorporated herein by reference.

For example, the condensation catalyst may also include a zeolite andother microporous supports that contain Group IA compounds, such as Li,Na, K, Cs and Rb. Preferably, the Group IA material may be present in anamount less than that required to neutralize the acidic nature of thesupport. A metal function may also be provided by the addition of groupVIIIB metals, or Cu, Ga, In, Zn or Sn. In some embodiments, thecondensation catalyst may be derived from the combination of MgO andAl₂O₃ to form a hydrotalcite material. Another condensation catalyst maycomprise a combination of MgO and ZrO₂, or a combination of ZnO andAl₂O₃. Each of these materials may also contain an additional metalfunction provided by copper or a Group VIIIB metal, such as Ni, Pd, Pt,or combinations of the foregoing.

The condensation reaction mediated by the condensation catalyst may becarried out in any reactor of suitable design, includingcontinuous-flow, batch, semi-batch or multi-system reactors, withoutlimitation as to design, size, geometry, flow rates, and the like. Thereactor system may also use a fluidized catalytic bed system, a swingbed system, fixed bed system, a moving bed system, or a combination ofthe above. In some embodiments, bi-phasic (e.g., liquid-liquid) andtri-phasic (e.g., liquid-liquid-solid) reactors may be used to carry outthe condensation reaction.

To facilitate a better understanding of the present invention, thefollowing examples of preferred embodiments are given. In no way shouldthe following examples be read to limit, or to define, the scope of theinvention.

EXAMPLES Comparative Example 1

Comparative Example 1 was conducted with reactants where the phenolicsconcentration was greater than 90% by weight based on the total weightof the reactants.

In Comparative Example 1, a 50-ml Parr 4590 reactor equipped with flatgasket Teflon seal was charged with 25 grams of 2-methoxy-4-propylphenol(MPP), 0.1 grams of potassium carbonate buffer, and 0.2 grams ofnickel-oxide promoted cobalt molybdate catalyst (DC-2534, containing1-10% cobalt oxide and molybdenum trioxide (up to 30 wt %) on alumina,and less than 2% nickel), obtained from Criterion Catalyst &Technologies L.P., and sulfided by the method described in Example 5 ofU.S. Application Publication No. 2010/0236988, the disclosure of whichis incorporated by reference in its entirety. The reactor was pressuredto 35 bar with H₂ (less than 1800 psi) and heated to 280° C. for 18hours, before sampling for analysis of products formed. The reactionconditions of the reactor simulated possible reaction conditions of thephenolics conversion unit described herein, except in ComparativeExample 1, the content has a phenolics concentration amount of greaterthan 50% by weight.

After sampling, the reactor was repressurized with H₂ to 35 bar, andheated to 300° C. again for 18 hours before sampling. A third cycle wascompleted with heating to 320° C. A third sampling was performed afterthe third cycle.

The reactor contents from the third sampling were analyzed by gaschromatography (GC) using a 60-m×0.32 mm ID DB-5 column of 1 μmthickness, with 50:1 split ratio, 2 ml/min helium flow, and column ovenat 40° C. for 8 minutes, followed by ramp to 285° C. at 10° C./min, anda hold time of 53.5 minutes. The injector temperature was set at 250°C., and the detector temperature was set at 300° C. The GC analysis ofthe third sample are shown in Table 1 below.

TABLE 1 Peak Ret # Time Area Name wt % 1 11.717 5619961 Propane 0.06% 211.982 6747590 dimethyl ether 0.07% 3 12.595 86782182 Methanol 0.91% 413.739 173280033 Acetone 1.82% 5 15.267 4461494 Cyclohexane 0.05% 615.787 5395829 Cyclohexene 0.06% 7 16.808 230550355 1-butanol 2.43% 818.937 4105220 propyl cyclopentane 0.04% 9 19.378 3171558 propylcyclopentene 0.03% 10 21.391 74035576 propyl cyclohexane 0.78% 11 22.00327587711 propyl cyclohexene 0.29% 12 22.147 37170017 propyl cyclohexene0.39% 13 22.717 20605421 Anisole 0.22% 14 22.792 93883327 propyl benzene0.99% 15 23.162 9515177 Cyclohexanone 0.10% 16 23.231 5293978Cyclohexanone 0.06% 17 23.887 9261343 methyl cyclohexanone 0.10% 1824.132 5497001 Unknown 0.06% 19 24.37 7327019 methyl propyl benzene0.08% 20 24.439 8573669 Unknown 0.09% 21 24.736 7409868 methyl propylbenzene 0.08% 22 25.39 4663686 Unknown 0.05% 23 25.529 296427426 Phenol3.12% 24 25.849 6417719 Unknown 0.07% 25 26.14 179442830 methoxy phenol1.89% 26 26.335 35159606 dimethoxy benzene 0.37% 27 26.516 100905315methyl phenol 1.06% 28 26.645 179198149 methoxy propyl benzene 1.89% 2926.724 380334055 methoxy propyl benzene 4.00% 30 26.923 49545038 methylmethoxy phenol 0.52% 31 27.067 29926443 dimethyl phenol 0.32% 32 27.1622258594 methyl methoxy phenol 0.23% 33 27.261 23251313 Unknown 0.24% 3427.329 19319037 methoxy methypropyl benzene 0.20% 35 27.387 52729332methoxy methypropyl benzene 0.56% 36 27.491 12532157 Unknown 0.13% 3727.548 11894399 Unknown 0.13% 38 27.679 10774905 Unknown 0.11% 39 27.789207630094 propyl phenol 2.19% 40 27.948 23890742 methoxy methypropylbenzene 0.25% 41 28.055 45934439 Unknown 0.48% 42 28.163 12471997Unknown 0.13% 43 28.407 2236905437 propyl phenol 23.55% 44 28.57929318453 methyl propyl phenol 0.31%

Example 2 According to Aspects Described Herein

A 450-ml Parr reactor was charged with a 20.02 grams ofmethoxypropylphenol and 190.01 grams of deionized water, both whichserved as the digestion solvent. The reactor was then charged with0.4192 grams of KOH buffer, and with 7.2522 grams of nickel-oxidepromoted cobalt molybdate catalyst (DC-2534, containing 1-10% cobaltoxide and molybdenum trioxide (up to 30 wt %) on alumina, and less than2% nickel), obtained from Criterion Catalyst & Technologies L.P., andsulfided by the method described in Example 5 of U.S. ApplicationPublication No. 2010/0236988.

The reactor was then charged with 14.02 grams of the pine wood ofnominal 12% moisture. Nominal 52 bar of hydrogen was added, and thereactor content was heated to 190° C. for 1 hour before ramping over 15minutes to a temperature of 245° C. for 2.5 hours, giving a total cycletime of 3.5 hours. The cycles were repeated with addition of 14.05,14.01, 14.04, 14.02, 13.99, 14.03, and 14.00 grams of pine wood. Thatis, the reactor was depressurized for each cycle as new pine wood wasadded then the reactor content was heated as described. All the wood wasdigested by the end of the 8^(th) cycle, which was determined bysubtracting the amount of solid from the weight of the catalyst. Theseeight cycles simulate the hydrothermal reaction that can take place inthe hydrothermal digestion unit described herein. The methoxy propylphenol serving as part of the initial digestion solvent simulates therecycling of unconverted phenolics from the separation zone to the firstreaction zone for use as part of the digestion solvent as describedherein. The phenolics concentration in the reactor content was less than50% by weight and the water concentration in the reactor content was atleast 10% by weight, both based on the total weight of the reactorcontent. A final cycle was conducted by heating the reactor content to270 degrees C. for 18 hours starting at 35 bar H₂ to simulate thehydrothermal reaction carried out in the phenolics conversion unitdescribed herein.

After the final cycle, 289.76 grams of the reaction mixture weredistilled to produce 230.5 grams of an overhead cut. An upper oily layercomprising 7% of the distilled mixture was analyzed by GCMS using a60-m×0.32 mm ID DB-5 column of 1 μm thickness, with 50:1 split ratio, 2ml/min helium flow, and column oven at 40° C. for 8 minutes, followed byramp to 285° C. at 10° C./min, and a hold time of 53.5 minutes. Theinjector temperature was set at 250° C., and the detector temperaturewas set at 300° C.

The result of the GC analysis is shown below in Table 2.

TABLE 2 Ret Peak # Time Area Name Area % 1 13.691 482012956 Cyclopentaneand 2.77% cyclopentene co-elute 2 14.568 135225173 methyl cyclopentane0.78% 3 15.062 206801927 methyl cyclopentene 1.19% 4 15.325 5811155372-butanol 3.34% 5 15.775 84326225 Cyclohexene 0.48% 6 16.044 92758002methyl THF 0.53% 7 16.606 101840672 ethyl cyclopentane 0.59% 8 16.818397513626 1-butanol 9 17.177 223913153 methyl cyclopentene 1.29% 1017.378 95437668 Unknown 0.55% 11 17.705 45625586 methyl cyclohexene0.26% 12 18.932 57603824 propyl cyclopentane 0.33% 13 19.356 2782634051-pentanol and propyl 1.60% cyclopentene co-elute 14 19.513 836356523-hexanone 0.48% 15 19.796 47634939 2-hexanone 0.27% 16 20.094 246657917Unknown 1.42% 17 20.299 101996105 Octahydropentalene 0.59% 18 20.699148727253 Cyclopentanone 0.86% 19 21.428 1113375735 propyl cyclohexane6.40% 20 21.641 119826018 methyl cyclopentanone 0.69% 21 21.74 108289044Unknown 0.62% 22 22.046 1021147457 propyl cyclohexene 5.87% 23 22.19793729707 propyl cyclohexene 4.57% 24 22.337 177977170 Unknown 1.02% 2522.801 290373711 propyl benzene 1.67% 26 22.958 119922371 Unknown 0.69%27 23.081 161499696 Unknown 0.93% 28 23.442 321904495 C9H14 1.85% 2923.596 329712365 ethyl cyclopentanone 1.90% 30 23.938 148557339 Unknown0.85% 31 24.387 69920701 Unknown 0.40% 32 24.588 93817820 Unknown 0.54%33 25.075 175481628 hexyl cyclopentanone 1.01% 34 25.569 145092583Unknown 0.83% 35 26.165 154464794 Unknown 0.89% 36 26.376 393093846propyl cyclohexanol 2.26% 37 26.503 860860070 propyl cyclohexanol 4.95%38 26.554 360807344 Unknown 2.08% 39 26.695 198109067 methyl propylphenol 1.14% 40 26.78 212189594 methoxy propyl benzene 1.22% 41 26.955565134459 Unknown 3.25% 42 27.058 230283141 propyl cyclohexanone 1.32%43 27.2 114973298 Unknown 0.66% 44 27.312 80318805 Unknown 0.46% 4527.494 94638259 ethyl phenol 0.54% 46 27.789 84629760 Unknown 0.49% 4728.221 110486524 methoxy ethyl phenol 0.64% 48 28.475 2823965694 Unknown16.24% 49 28.991 228746231 Unknown 1.32% 50 29.252 1591152593 methoxypropyl phenol 9.15% 51 29.308 765453976 methoxy propyl phenol 4.40% 5229.633 132262581 diethyl phenol 0.76% 53 29.805 82285232 dimethoxypropyl benzene 0.47% 54 30.532 99103120 Unknown 0.57%

Analysis

The results of Comparative Example 1 and Example 2 indicate that asecond hydrothermal reaction of a reaction product of an in situcatalytic reduction reaction in the presence of molecular hydrogen and acatalyst capable of activating molecular hydrogen can provide forproduction of hydrocarbons from phenolics. However, the yields ofhydrocarbon products can be increased if the concentration of phenolicswas low and the lignin reversion, including lignin to phenols and/orconversion of phenolics to hydrocarbon compounds, takes place in thepresence of water. In particular, where the content of the secondhydrothermal reaction has a phenolics concentration of equal to or lessthan 50% by weight and a water concentration of at least 10% by weight,based on the total weight of the reaction content of the secondhydrothermal reaction, at least the conversion of phenolics tohydrocarbons can be improved by about 10-fold, as shown in Example 2.

The phenolics concentration for Comparative Example 1 simulating thephenolics conversion unit described herein was greater than 90% based ontotal weight of the reactor content. In comparison, the phenolicsconcentration for the reaction simulating the phenolics conversion unitdescribed herein in Example 2 was below 50% based on total weight of thereactor content. Example 2 provided for an estimated 65% conversionrelative to the phenolics remaining unconverted. Table 2 shows that inaddition to the initial digestion solvent that included methoxy propylphenol, a range of alkanes, ketone and aldehyde monooxygenates as wellas glycol solvents and products, and polyols (glycerol) were observed,with volatility greater than C6 sugar alcohol sorbitol. For instance,Table 2 shows the amount of alkanes and alkenes observed was at leastabout 20.4%, which included propyl cyclohexane, propyl cyclohexene,propyl benzene, and C₉H₁₄. Other products observed were propylcyclohexanol, methoxy propyl benzene, and propyl cyclohexanone.

Table 1 of Comparative Example 1 shows the amount of propyl cyclohexanewas 0.78% as compared to 6.4% in Table 2; the amount of propylcyclohexene in Table 1 was 0.68% as compared to about 10.5% in Table 2,the amount of propyl benzene in Table 1 was about 1% as compared to1.67% in Table 2; and Table 1 did not show any trace of C₉H₁₄ ascompared to 1.85% in Table 2. The amount of phenolics in Table 1,including propyl phenol, was about 30% as compared to about 14% in Table2.

Accordingly, the examples indicate that a substantial portion of thephenolic compounds present as solvent or formed via digestion of wood,can be converted to hydrocarbons derived from phenolics, such ascycloalkanes and its alkyl substituents or derivatives and cycloalkenesand its alkyl substituents or derivatives via the methods and systemsdescribed herein. Moreover, these reaction products are observed to bemore volatile than the unconverted phenols, as evidenced by earlierelution on the GC trace, thereby allowing for easier separation ofphenolics from the reaction product and subsequent recycling asdescribed herein.

Therefore, the present invention is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular embodiments disclosed above are illustrative only, as thepresent invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is therefore evident that theparticular illustrative embodiments disclosed above may be altered,combined, or modified and all such variations are considered within thescope and spirit of the present invention. The invention illustrativelydisclosed herein suitably may be practiced in the absence of any elementthat is not specifically disclosed herein and/or any optional elementdisclosed herein. While compositions and methods are described in termsof “comprising,” “containing,” or “including” various components orsteps, the compositions and methods may also “consist essentially of” or“consist of” the various components and steps. All numbers and rangesdisclosed above may vary by some amount. Whenever a numerical range witha lower limit and an upper limit is disclosed, any number and anyincluded range falling within the range is specifically disclosed. Inparticular, every range of values (of the form, “from about a to aboutb,” or, equivalently, “from approximately a to b,” or, equivalently,“from approximately a-b”) disclosed herein is to be understood to setforth every number and range encompassed within the broader range ofvalues. Also, the terms in the claims have their plain, ordinary meaningunless otherwise explicitly and clearly defined by the patentee.Moreover, the indefinite articles “a” or “an,” as used in the claims,are defined herein to mean one or more than one of the element that itintroduces. If there is any conflict in the usages of a word or term inthis specification and one or more patent or other documents that may beincorporated herein by reference, the definitions that are consistentwith this specification should be adopted.

What is claimed is:
 1. A method comprising: providing a first reactioncontent to a reactor in a first reaction zone, where the first reactioncontent comprises cellulosic biomass solids, molecular hydrogen, acatalyst capable of activating molecular hydrogen, and a digestionsolvent; heating the first reaction content to form a first reactionproduct comprising phenolics and an alcoholic component; providing asecond reaction content to a reactor in a second reaction zone, wherethe second reaction content comprises the first reaction product,molecular hydrogen, and a catalyst capable of activating molecularhydrogen; heating the second reaction content to form a second reactionproduct comprising hydrocarbons converted from phenolics and unconvertedphenolics, providing the reactor in the second reaction zone withconditions configured to generate molecular hydrogen, wherein at leastone of said conditions comprises providing the reactor in the secondreaction zone with a pressure of less than 200 bar; separating anunconverted phenolics fraction from the second reaction product;providing a first portion of the unconverted phenolics fraction to thereactor in the first reaction zone; and providing a second portion ofthe unconverted phenolics fraction to the reactor in the second reactionzone.
 2. The method of claim 1 wherein the second reaction content has aconcentration of phenolics of 50% or less by weight based on the totalweight of the second reaction content.
 3. The method of claim 1 whereinthe second reaction content has a water concentration of at least 10% byweight based on the total weight of the second reaction content.
 4. Themethod of claim 1 wherein the unconverted phenolics fraction comprisesgreater than 50% of the amount of phenolics in the second reactionproduct from which the unconverted phenolics fraction is separated. 5.The method of claim 1 wherein at least a portion of triols and glycol inthe alcoholic component is converted to monohydric alcohols.
 6. Themethod of claim 1 wherein the first reaction content is heated to atemperature in a range of about 190 to 260 degrees C.
 7. The method ofclaim 1 wherein the second reaction content is heated to a temperaturein a range of about 210 to 300 degrees C.
 8. The method of claim 1wherein the reactor in the first reaction zone has a total pressure ofat least 30 bar.
 9. The method of claim 1 wherein the reactor in thesecond reaction zone has a total pressure of at least 30 bar.
 10. Themethod of claim 1 wherein the reactor in the second reaction zone has atotal pressure that is lower than a total pressure of the reactor in thefirst reaction zone.
 11. The method of claim 1 wherein the hydrocarbonsconverted from phenolics comprise at least one of an alkane, an alkene,a cycloalkane, a cycloalkene, an alkyl derivative or substituent of thecycloalkane, and an alkenealkyl derivative or substituent of thecycloalkene.
 12. The method of claim 1, wherein the catalyst in thefirst reaction content comprises fluidly mobile catalyst particulates.13. The method of claim 12, wherein the catalyst in the reactor in thesecond reaction content comprises fluidly mobile catalyst particulates.14. The method of claim 13, wherein the fluidly mobile catalystparticulates in the second reaction content comprise fluidly mobilecatalyst particulates from the first reaction content.
 15. The method ofclaim 1, wherein at least one of the first reaction zone and the secondreaction zone comprises a slurry reactor.
 16. The method of claim 1,wherein at least one of the first reaction zone and the second reactionzone comprises an ebullating bed reactor.
 17. The method of claim 1wherein the first reaction zone comprises an ebulatting bed reactor andthe second reaction zone comprises at least one of a fixed bed reactorand a trickle bed reactor.
 18. The method of claim 1, furthercomprising: providing to the reactor in the second reaction zone acatalyst different from the catalyst in the reactor in the firstreaction zone.
 19. The method of claim 1 further comprising increasingthe catalytic activity in the reactor in the second reaction zone toincrease hydrogen generation.
 20. The method of claim 1, wherein thefirst reaction zone comprises a slurry reactor and the second reactionzone comprises at least one of a fixed bed reactor and a trickle bedreactor.